Assessing extreme loads on a tidal turbine using focused wave groups in energetic currents

Tidal stream turbines are subject to large hydrodynamic loads, including those induced by extreme waves. Scale model testing in the laboratory plays an important role in ensuring that full scale tidal turbines are designed and operated in a manner that is appropriate for harsh ocean environments where waves and tidal currents coexist.For the first time, a fully-instrumented scaled tidal turbine is tested in short-duration focused wave groups representative of extreme environmental load cases expected at energetic tidal sites. In this paper, the subsequent variations in rotor-based loads, power and blade root bending moments are reported. These measurements are found to strongly follow the spectral and temporal form of the focused wave conditions, and peak loads and power output are found to exceed current-only values by 85% and 200% respectively. These rotor-averaged values display a high level of repeatability, demonstrating the suitability of focused waves for testing seabed-mounted tidal turbines. Extreme blade loads, which are dependent on angular position relative to wave phase, are captured through rapidly obtained repeat tests. New insight is subsequently gained into loading and response of tidal turbines in extreme sea conditions

Sodium and potassium relationships in sugar beet

RESP-619

Effects of soil compaction on yield and fertilizer requirement of sugar beet

RESP-629

Nitrogen requirement of sugar beet grown on mineral soils

The effect of nitrogen fertilizer on the yield of sugar beet was tested in 170 experiments done between 1957 and 1966; results of 88 experiments, some testing five and six amounts of N, have not previously been published. On most sites, nitrogen increased sugar yields sharply and almost linearly up to an optimum beyond which yield changed little or decreased only slightly up to 1·8 cwt N/acre, the largest amount tested. In the two series of experiments giving most information, the mean increase from sub-optimal amounts of N was 2·5 cwt sugar/0·1 cwt N/acre. Usually 0·4–0·8 cwt N/acre was enough for maximum yield; more was needed on a few sites and on about a fifth of them nitrogen fertilizer was not needed. In 7 of the 10 years, the average optimum was 0·6–0·8 cwt N/acre; less was needed in the other years, the driest three years of the decade. In most, though not all, years, site-to-site differences in response between 0·9 and 1·8 cwt N/acre were no greater than could be expected from experimental error alone; much of the apparent difference in response between seasons were also attributable to this source. After taking account of experimental error, there were substantial between-site differences in response to amounts of N up to 0·9 cwt/acre, but attempts to explain them in terms of weather, soil and husbandry factors had little success. There was slight evidence of diminished responses to N where sugar beet followed crops other than cereals, and of responses somewhat greater than average on Chalky Boulder Clay soils of the Hanslope and Stretham Series; no other relationships were large or consistent enough to be useful for prediction. As between-site differences in response are largely unpredictable, and because a grower risks much greater crop losses by applying too little N than by applying too much, the recommended dressing is 1·0 cwt N/acre, substantially more than is needed, on the average, to obtain maximum yield. More N should be given on soils of the Hanslope and Stretham Series and on light sands poor in organic matter; less need be applied where crop residues are likely to supply much nitrogen. RESP-613

Impact of pandemic service changes on ethnic inequalities in maternal and perinatal outcomes in England: a population-based study.

OBJECTIVE: In the UK and worldwide, there are substantial ethnic inequalities in maternal and perinatal care and outcomes. We aim to assess the impact of the unprecedented change in care provision during the COVID-19 pandemic on inequalities in adverse maternity outcomes. DESIGN: Retrospective cohort study using structured electronic health record data. SETTING: English hospital trusts providing maternity care. PARTICIPANTS: Women giving birth and babies born in the National Health Service (NHS) in England between 1 April 2018 and 31 March 2021, in three time groups: prepandemic, the first pandemic wave (26 March 2020 to 30 June 2020) and second pandemic wave (1 July 2020 to 31 March 2021). Self-reported ethnicity was grouped into White, South-Asian, Black, Mixed and Other. MAIN OUTCOME MEASURES: Composite and component measures of maternal (emergency caesarean section, obstetric anal sphincter injury, hysterectomy, sepsis, anaesthetic complications and prolonged hospital stay) and perinatal (stillbirth, neonatal death, preterm birth, brain injury, small for gestational age and prolonged hospital stay). Poisson regression was used to compare relative risks between different ethnic groups. FINDINGS: 1.54 million maternal and 1.43 million neonatal records were included. The overall incidence of adverse outcomes per 1000 births initially decreased maternal: from 308.0 (95% CI 307.0 to 309.0) to 291.0 (95% CI 311.4 to 314.9) (p<0.001); perinatal: from 133.0 (95% CI 132.3 to 133.7) to 111.9 (95% CI 110.1 to 113.7) (p<0.001)), but then increased in the second pandemic period (maternal: 313.2 (95% CI 311.4 to 314.9) (p<0.001); perinatal 118.9 (95% CI 117.7 to 120.0) (p<0.001)). The risk of adverse outcomes was higher in women and babies from all ethnic minority groups compared with White women in both pandemic periods. Black and South-Asian women and babies were approximately 25% more likely to sustain adverse outcomes. While similar overall changes in adverse outcomes were seen in all groups, existing inequalities were sustained throughout the pandemic periods. INTERPRETATION: Existing inequalities in adverse maternal and perinatal/neonatal outcomes were maintained, not tempered, during the pandemic, despite substantial changes to maternity services and care. Further research on possible interventions to reduce inequality is needed

An experimental investigation into non-linear wave loading on horizontal axis tidal turbines

Tidal turbines are subject to large hydrodynamic loads from combinations of currents and waves, which contribute significantly to fatigue, extreme loading and power flow requirements. Physical model testing enables these loads and power fluctuations to be assessed and understood in a controlled and repeatable environment. In this work, a 1:15 scale tidal turbine model is utilised to further the fundamental understanding of the influence of waves on tidal turbines. A wide range of regular waves are generated in both following-current and opposing-current conditions. Wave frequencies range from 0.31 Hz to 0.55 Hz & wave heights from 0.025 m to 0.37 m in a fixed 0.81 m/s current velocity. Waves are selected and programmed specifically to facilitate frequency domain analysis, and techniques are employed to isolate the effect of non-linear waves on turbine power and thrust. Results demonstrate that wave action induces large variations in turbine power and thrust compared to current only conditions. For the range of conditions tested, peak values of thrust and power exceed current-only values by between 7%–65% and 13%–160% respectively. These wave-induced fluctuations are shown to increase with wave amplitude and decrease with wave frequency. Following wave conditions exhibit greater variations than opposing for waves with the same wave height and frequency due to the lower associated wavenumbers. A model is developed and presented to aid the understanding of the high-order harmonic response of the turbine to waves, which is further demonstrated using steady state coefficients under assumptions of pseudo-stationarity. This approach is proven to be effective at estimating wave-induced power and thrust fluctuations for the combinations of waves, currents and turbine state tested. The outcome of which shows promise as a rapid design tool that can evaluate the effect of site-specific wave–current conditions on turbine performance

Temporal trends in stillbirth over eight decades in England and Wales: A longitudinal analysis of over 56 million births and lives saved by improvements in maternity care.

Background: Considering the public health importance of stillbirth, this study quantified the trends in stillbirths over eight decades in England and Wales. Methods: This longitudinal study utilized the publicly available aggregated data from the Office for National Statistics that captured maternity information for babies delivered in England and Wales from 1940 to 2019. We computed the trends in stillbirth with the associated incidence risk difference, incidence risk ratio, and extra lives saved per decade. Results: From 1940-2019, 56 906 273 births were reported. The stillbirth rate declined (85%) drastically up to the early 1980s. In the initial five decades, the estimated number of deaths per decade further decreased by 67 765 (9.49/1000 births) in 1940-1949, 2569 (0.08/1000 births) in 1950-1959, 9121 (3.50/1000 births) in 1960-1969, 15 262 (2.31/1000 births) in 1970-1979, and 10 284 (1.57/1000 births) in 1980-1989. However, the stillbirth rate increased by an additional 3850 (0.58/1000 births) stillbirths in 1990-1999 and 693 (0.11/1000 births) stillbirths in 2000-2009. The stillbirth rate declined again during 2010-2019, with 3714 fewer stillbirths (0.54/1000 births). The incidence of maternal age 35 years) increased. Conclusions: The stillbirth rate declined drastically, but the rate of decline slowed in the last three decades. Though teenage pregnancy (<20 years) had reduced, the prevalence of women with a higher risk of stillbirth may have risen due to an increase in advanced maternal age. Improved, more personalised care is required to reduce the stillbirth rate further

A positive deviant approach to examining the impact of Covid-19 on ethnic inequalities in maternal and neonatal outcomes

This is the final version. Available on open access from Elsevier via the DOI in this recordOBJECTIVES: During the COVID-19 pandemic, rapid and heterogeneous changes were made to maternity care. Identification of changes that may reduce maternal health inequalities is a national priority. The aim of this project was to use data collected about care and outcomes to identify NHS Trusts in the UK where inequalities in outcomes reduced during the pandemic and explore through interviews how the changes that occurred may have led to a reduction in inequalities. METHODS: A Women's Reference Group of public advisors guided the project. Analysis of Hospital Episode Statistics Admitted Patient Care data of 128 organisations in England identified "positive deviant" organisations that reduced inequalities, using maternal and perinatal composite adverse outcome indicators. Positive deviant organisations were identified for investigation, alongside comparators. Senior clinicians, heads of midwifery and representatives of women giving birth were interviewed. Reflexive thematic analysis was employed. RESULTS: The change in the inequality gap for the maternal indicator ranged from a reduction of -0.24 to an increase of 0.30 per 1000 births between the pre-pandemic and pandemic period. For the perinatal composite indicator, the change in inequality gap ranged from -0.47 to 0.67 per 1000 births. Nine Trusts were identified as positive deviants and 10 as comparators. We conducted 20 interviews from six positive deviant and four comparator organisations. Positive deviants reported that necessary shifts in roles led to productive and novel use of expert staff; comparators reported senior staff 'stepping in' where needed and no benefits of this. They reported proactivity and quick reactions, increased team working, and rapid implementation of new ideas. Comparators found constant changes overwhelming, and no increase in team working. No specific differences in care processes were identified. CONCLUSIONS: Harnessing proactivity, flexibility, staffing resource, and increased team working proves vital in reducing health inequalities.THIS institut

Disparities in stillbirths in England: analysis of a population‐based study of 1.3 million births

Objective To examine the variation in stillbirth rates between different ethnic and socioeconomic groups within each organisational hospital group (health trust). Design National registry study. Setting All health trusts (HT) in National Health Service England. Population All mothers and babies born between April 2015 and March 2017. Methods This observational study examined ethnic and socioeconomic disparities in stillbirth rates for 1 268 367 births in 133 HTs compared to the national average. Outcome Stillbirth at or after 24 gestational weeks. Results The average stillbirth rates ranged from 3.4/1000 births for White women up to 7.1/1000 births for Black women. The rates ranged from 2.9/1000 births for women living in the least deprived areas to 4.7/1000 births for those in the most deprived. The proportions of HTs with stillbirth rates well above the national average (more than 2 standard deviations) for White, Asian and Black women were 0.8%, 21.8% and 38.6%, respectively. When HTs were ranked by stillbirth rate, there were notable variations, with some trusts demonstrating lower than average stillbirth rates for White women while concurrently having higher than average stillbirth rates for Asian and/or Black women. There were no units exhibiting lower than national average stillbirth rates for Asian/Black women while concurrently having higher than average stillbirth rates for White women. Conclusions These findings suggest that access to and delivery of maternity care vary depending on the mother's ethnicity and level of socioeconomic deprivation. Social factors are likely determinants of inequality in stillbirth rather than maternity care alone