399 research outputs found

    Wildlife overpass structure size, distribution, effectiveness, and adherence to expert design recommendations

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    It is now well evidenced that wildlife crossing structures paired with exclusion fencing reduce wildlife vehicles collisions while facilitating wildlife connectivity across roadways. Managing animal mortality and subpopulation connectivity is crucial to successful species and landscape stewardship. Highway mitigation projects are large economic investments that remain on the landscape for many decades. Governments and planning agents thus strive to balance cost and benefit to build cost-effective structures with the greatest positive impact on local wildlife and motorists. Ideal dimensions of overpasses and underpasses vary by species, but scientists generally suggest that overpasses for large mammals should be approximately 50 m wide. Optimal width also depends on structure length, with longer structures requiring additional width. Accordingly, experts have suggested a width to length ratio of 0.8. We sought to assess how these recommendations manifested in practice—where agencies use this information to design and build structures while also balancing cost and logistical challenges—and the degree to which built structures conform to current recommendations. We identified 120 wildlife overpasses across the world that were constructed to reduce the negative impacts of roads. Using a novel measurement technique, we analyzed the dimensions of these 120 overpasses located in North America, Europe, Asia, and Oceania. The average width of the wildlife overpasses was 34 m. Most wildlife overpasses located in North America and Europe did not meet their respective dimensional expert guidelines. We investigate reasons explaining the non-compliance and provide recommendations for future overpass designs. Building on previous evidence showing that wider overpasses have increased crossing rates, we examined crossing rates for multiple large mammal species across 12 overpasses located in western North America. We qualitatively observed that wider North American overpasses (40–60 m), in or near compliance with expert guidelines, were associated with a more diverse set of species use and had nearly twice the average crossing rates when compared to non-compliant, narrow North American overpasses. In reviewing various studies from around the world, we conclude that wide overpasses (~50 m) continue to present ecologically sound and cost-effective solutions for decreasing the barrier of roadways, especially when targeting width-sensitive species and large assemblages of mammals. Future studies, however, are encouraged to further explore the specific instances when underpasses and narrower overpasses present more cost-effective ecological solutions, or how these structures can complement wide overpasses in successful wildlife crossing systems

    The hydrogenation of mandelonitrile over a Pd/C catalyst: towards a mechanistic understanding

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    A carbon supported Pd catalyst is used in the liquid phase hydrogenation of the aromatic cyanohydrin mandelonitrile (C6H5CH(OH)CH2CN) to afford the primary amine phenethylamine (C6H5CH2CH2NH2). Employing a batch reactor, the desired primary amine is produced in 87% selectivity at reaction completion. Detection of the by-product 2-amino-1-phenylethanol (C6H5CH(OH)CH2NH2) accounts for the remaining 13% and closes the mass balance. The reaction mechanism is investigated, with a role for both hydrogenation and hydrogenolysis processes established

    The production of tyramine via the selective hydrogenation of 4-hydroxybenzyl cyanide over a carbon-supported palladium catalyst

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    The selective production of primary amines is a problem that plagues heterogeneously catalysed nitrile hydrogenation reactions. Whilst the target amine tyramine (HOC6H4CH2CH2NH2) is biochemically available through the action of enzymes, synthetic routes to this species are not widely reported. Here, a heterogeneously catalysed method is proposed that utilises a Pd/C catalyst to effect the selective hydrogenation of 4-hydroxybenzyl cyanide within a three-phase reactor. The aforementioned selectivity issues are overcome by adjustment of various experimental parameters (hydrogen supply, agitation rate, temperature, use of an auxiliary agent) that result in improved catalytic performance, such that the desired tyramine salt (tyramine hydrogen sulphate) can be produced in quantitative yield. Accordingly, through consideration of the interconnectivity of hydrogenation and hydrogenolysis processes, a selective synthetic strategy is achieved with the findings suitable for extension to other substrates of this nature

    Программные средства компьютерного моделирования электромеханического пуска гидрогенератора

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    Increasing and variable traffic demands due to triple play services pose significant Internet Protocol Television (IPTV) resource management challenges for service providers. Managing subscriber expectations via consolidated IPTV quality reporting will play a crucial role in guaranteeing return-on-investment for players in the increasingly competitive IPTV delivery ecosystem. We propose a fault diagnosis and problem isolation solution that addresses the IPTV monitoring challenge and recommends problem-specific remedial action. IPTV delivery-specific metrics are collected at various points in the delivery topology, the residential gateway and the Digital Subscriber Line Access Multiplexer through to the video Head-End. They are then pre-processed using new metric rules. A semantic uplift engine takes these raw metric logs; it then transforms them into World Wide Web Consortium’s standard Resource Description Framework for knowledge representation and annotates them with expert knowledge from the IPTV domain. This system is then integrated with a monitoring visualization framework that displays monitoring events, alarms, and recommends solutions. A suite of IPTV fault scenarios is presented and used to evaluate the feasibility of the solution. We demonstrate that professional service providers can provide timely reports on the quality of IPTV service delivery using this system.QC 20150921EOLA

    Effects of gender-transformative relationships and sexuality education to reduce adolescent pregnancy (The JACK trial): a cluster randomised trial

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    BACKGROUND: The need to engage boys in gender-transformative relationships and sexuality education (RSE) to reduce adolescent pregnancy is endorsed by WHO. We aimed to test an intervention which used a gender-transformative approach to engage adolescents in RSE to prevent unprotected sex. METHODS: This cluster-randomised trial with process and economic evaluations tested a school-based intervention entitled If I Were Jack versus standard RSE (control) for students (aged 14-15 years) in UK schools. Schools were randomly allocated (1:1) and masked to allocation at baseline. The primary outcome was self-reported avoidance of unprotected sex (sexual abstinence or use of reliable contraception at last sex) after 12-14-months. We analysed the data using intention-to-treat mixed effects regression models. FINDINGS: Of 803 schools assessed for eligibility, 263 schools were invited by letter, of which 66 schools agreed to be randomly assigned, of which 62 schools completed follow-up. The trial was done between Feb 1, 2018, and March 6, 2020. 8216 students participated at baseline in 2018; 6561 (79·85%) provided 12-14 months follow-up. There was no significant difference in the primary outcome of avoidance of unprotected sex: 2648 (86·62) of 3057 in the intervention group avoided unprotected sex versus 2768 (86·41%) of 3203 in the control group (adjusted odds ratio [aOR] 0·85 [95% CI 0·58-1·26], p=0·42). Exploratory post-hoc analysis of the two components of the primary outcome showed that significantly more intervention students used reliable contraception at last sex compared with control students and there was no significant difference between the groups for sexual abstinence. No adverse events were reported. INTERPRETATION: The intervention had a null effect on the primary outcome of preventing unprotected sex (increasing sexual abstinence or use of reliable contraception) in the whole student population. However, the results showed significant increases in use of reliable contraceptives for sexually active students. Engaging all young people early through RSE is important so that as they become sexually active, rates of unprotected sex are reduced. FUNDING: National Institute for Health Research

    School-based relationship and sexuality education intervention engaging adolescent boys for the reductions of teenage pregnancy: the JACK cluster RCT

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    BACKGROUND: The need to engage boys in gender-transformative relationships and sexuality education (RSE) to reduce adolescent pregnancy is endorsed by the World Health Organization and the United Nations Educational, Scientific and Cultural Organization. OBJECTIVES: To evaluate the effects of If I Were Jack on the avoidance of unprotected sex and other sexual health outcomes. DESIGN: A cluster randomised trial, incorporating health economics and process evaluations. SETTING: Sixty-six schools across the four nations of the UK. PARTICIPANTS: Students aged 13-14 years. INTERVENTION: A school-based, teacher-delivered, gender-transformative RSE intervention (If I Were Jack) versus standard RSE. MAIN OUTCOME MEASURES: Self-reported avoidance of unprotected sex (sexual abstinence or reliable contraceptive use at last sex) after 12-14 months. Secondary outcomes included knowledge, attitudes, skills, intentions and sexual behaviours. RESULTS: The analysis population comprised 6556 students: 86.6% of students in the intervention group avoided unprotected sex, compared with 86.4% in the control group {adjusted odds ratio 0.85 [95% confidence interval (CI) 0.58 to 1.26], p = 0.42}. An exploratory post hoc analysis showed no difference for sexual abstinence [78.30% intervention group vs. 78.25% control group; adjusted odds ratio 0.85 (95% CI 0.58 to 1.24), p = 0.39], but more intervention group students than control group students used reliable contraception at last sex [39.62% vs. 26.36%; adjusted odds ratio 0.52 (95% CI 0.29 to 0.920), p = 0.025]. Students in schools allocated to receive the intervention had significantly higher scores on knowledge [adjusted mean difference 0.18 (95% CI 0.024 to 0.34), p = 0.02], gender-equitable attitudes and intentions to avoid unintended pregnancy [adjusted mean difference 0.61 (95% CI 0.16 to 1.07), p = 0.01] than students in schools allocated to receive the control. There were positive but non-significant differences in sexual self-efficacy and communication skills. The total mean incremental cost of the intervention compared with standard RSE was £2.83 (95% CI -£2.64 to £8.29) per student. Over a 20-year time horizon, the intervention is likely to be cost-effective owing to its impact on unprotected sex because it would result in 379 (95% CI 231 to 477) fewer unintended pregnancies, 680 (95% CI 189 to 1467) fewer sexually transmitted infections and a gain of 10 (95% CI 5 to 16) quality-adjusted life-years per 100,000 students for a cost saving of £9.89 (95% CI -£15.60 to -£3.83). LIMITATIONS: The trial is underpowered to detect some effects because four schools withdrew and the intraclass correlation coefficient (0.12) was larger than that in sample size calculation (0.01). CONCLUSIONS: We present, to our knowledge, the first evidence from a randomised trial that a school-based, male engagement gender-transformative RSE intervention, although not effective in increasing avoidance of unprotected sex (defined as sexual abstinence or use of reliable contraception at last sex) among all students, did increase the use of reliable contraception at last sex among students who were, or became, sexually active by 12-14 months after the intervention. The trial demonstrated that engaging all adolescents early through RSE is important so that, as they become sexually active, rates of unprotected sex are reduced, and that doing so is likely to be cost-effective. FUTURE WORK: Future studies should consider the longer-term effects of gender-transformative RSE as students become sexually active. Gender-transformative RSE could be adapted to address broader sexual health and other settings. TRIAL REGISTRATION: This trial is registered as ISRCTN10751359. FUNDING: This project was funded by the National Institute for Health and Care Research (NIHR) Public Health Research programme (PHR 15/181/01) and will be published in full in Public Health Research; Vol. 11, No. 8. See the NIHR Journals Library website for further project information
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