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"Verhoef, Hans"
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A probabilistic long‐term framework for site‐specific erosion analysis of wind turbine blades: A case study of 31 Dutch sites
by
Ren, Zhengru
,
Castro, Saullo G.P.
,
Teuwen, Julie J.E.
in
Case studies
,
coatings
,
leading‐edge erosion
2021
Rain‐induced leading‐edge erosion (LEE) of wind turbine blades (WTBs) is associated with high repair and maintenance costs. The effects of LEE can be triggered in less than 1 to 2 years for some wind turbine sites, whereas it may take several years for others. In addition, the growth of erosion may also differ for different blades and turbines operating at the same site. Hence, LEE is a site‐ and turbine‐specific problem. In this paper, we propose a probabilistic long‐term framework for assessing site‐specific lifetime of a WTB coating system. Case studies are presented for 1.5 and 10 MW wind turbines, where geographic bubble charts for the leading‐edge lifetime and number of repairs expected over the blade's service life are established for 31 sites in the Netherlands. The proposed framework efficiently captures the effects of spatial and orographic features of the sites and wind turbine specifications on LEE calculations. For instance, the erosion is highest at the coastal sites and for sites located at higher altitudes. In addition, erosion is faster for turbines associated with higher tip speeds, and the effects are critical for such sites where the exceedance probability for rated wind conditions are high. The study will aid in the development of efficient operation and maintenance strategies for wind farms.
Journal Article
Comparison of haemoglobin concentration measurements using HemoCue-301 and Sysmex XN-Series 1500: A survey among anaemic Gambian infants aged 6–12 months
2024
In low-income countries, point-of-care photometers are used in the screening and management of anaemia in individuals, but also in the assessment of population iron status when evaluating efficacy of intervention studies or public health interventions.
We aimed to evaluate the accuracy of a commonly used photometer, HemoCue-301, in determining haemoglobin concentration among anaemic children aged 6-12 months in a field setting in rural Africa.
This report concerns a secondary analysis of data from Gambian infants being screened for an ongoing randomized controlled trial. In those found to be anaemic by HemoCue-301, haemoglobin concentration was measured by Sysmex XN-1500, an automated haematology analyser that was used as a reference. Passing-Bablok regression analysis was used to estimate the regression constant (systematic deviation between two measurement methods that remain consistent across the range of measurements) and proportional bias (systematic deviation between two measurement methods that change in magnitude relative to the value being measured).
Analysis was based on 227 participants. There was strong evidence of absolute bias among moderately anaemic participants (haemoglobin concentration at 8.0g/dL) (absolute bias: 1.12g/dL; 95% CI: 0.91 to 1.37g/dL; proportional bias: 14.0%; 95% CI: 11.4% to 17.1%) in haemoglobin concentrations measured by HemoCue-301 compared to those measured by Sysmex XN-Series1500. Bias was marginal at haemoglobin concentration of 11.0g/dL (absolute bias: -0.08g/dL; 95% CI: -0.18 to 0.07g/dL; proportional bias: -7.3%; 95% CI: -6.5% to 0.6%).
Haemoglobin measurements by HemoCue-301 seem substantially biased in participants with haemoglobin less than 8.0g/dL.
Journal Article
Improving diets and nutrition through an integrated poultry value chain and nutrition intervention (SELEVER) in Burkina Faso: study protocol for a randomized trial
2017
Background
The SELEVER study is designed to evaluate the impact of an integrated agriculture–nutrition package of interventions (including poultry value chain development, women’s empowerment activities, and a behavior change communications strategy to promote improved diets and feeding, care, and hygiene practices) on the diets, health, and nutritional status of women and children in Burkina Faso. This paper presents the rationale and study design.
Methods
The impact evaluation involves a cluster randomized controlled trial design that will be implemented in 120 rural communities/villages within 60 communes supported by SELEVER in the Boucle de Mouhoun, Centre-Ouest, and Haut-Bassins regions of Burkina Faso. Communities will be randomly assigned to one of three treatment arms, including: (1) SELEVER intervention group; (2) SELEVER with an intensive WASH component; and (3) control group without intervention. Primary outcomes include the mean probability of adequacy of diets for women and children (aged 2–4 years at baseline), infant and young child feeding practices of caregivers of children aged 0–2 years, and household poultry production and sales. Intermediate outcomes along the agriculture and nutrition pathways will also be measured, including child nutrition status and development. The evaluation will follow a mixed-methods approach, including a panel of child-, household-, community-, and market-level surveys, and data collection points during post-harvest and lean seasons, as well as one year after implementation completion to examine sustainability.
Discussion
To our knowledge, this study is the first to rigorously examine from a food systems perspective, the simultaneous impact of scaling-up nutrition-specific and nutrition-sensitive interventions through a livestock value-chain and community-intervention platform, across nutrition, health, and agriculture domains. The findings of this evaluation will provide evidence to support the design of market-based nutrition-sensitive interventions.
Trial registration
ISRCTN registry,
ISRCTN16686478
. Registered on 2 December 2016.
Journal Article
Depressive symptoms among Mexican adolescent girls in relation to iron status, anaemia, body weight and pubertal status: results from a latent class analysis
by
Woods, Bo-Jane
,
Quiroga-Garza, Angelica
,
Zarate-Ortiz, Arli Guadalupe
in
Adolescence
,
Adolescents
,
Anaemia
2023
The study examined the association between depressive symptoms and iron status, anaemia, body weight and pubertal status among Mexican adolescent girls.
In this cross-sectional study, depressive symptoms were assessed by the 6-item Kutcher Adolescent Depression Scale, and latent class analysis (LCA) was used to identify and characterise groups of girls based on depressive symptoms. Iron status and inflammation were assessed using ferritin and soluble transferrin receptor, C-reactive protein and alpha-1-acid glycoprotein, respectively. Multiple logistic and linear regressions were applied to model class membership as a function of iron status, anaemia, body weight and pubertal status.
We collected data from 408 girls aged 12-20 years.
Public schools in northern Mexico.
LCA yielded three classes of depressive symptoms: 44·4 % of the adolescents were 'unlikely to be depressed', 41·5 % were 'likely to be depressed' and 14·1 % were 'highly likely to be depressed'. Our analyses demonstrated that iron-deficient girls had greater odds of being 'likely depressed' (OR 2·01, 95 % CI 1·01, 3·00) or 'highly likely depressed' (OR 2·80, 95 % CI 1·76, 3·84). Linear regression analyses revealed that lower Hb concentrations and higher body weight increased the probability of being 'likely depressed'. There was no evidence that depressive symptoms were associated with age at menarche and years since menstruation.
This study shows that iron-deficient adolescent girls are more likely to suffer from depressive symptoms and that lower concentrations of Hb and higher body weight increased the probability of experiencing depressive symptoms.
Journal Article
Haem iron versus ferrous iron salts to treat iron deficiency anaemia in Gambian children: protocol for randomised controlled trial {1}
2024
Background
The World Health Organization recommends universal iron supplementation for children aged 6–23 months in countries where anaemia is seen in over 40% of the population. Conventional ferrous salts have low efficacy due to low oral absorption in children with inflammation. Haem iron is more bioavailable, and its absorption may not be decreased by inflammation. This study aims to compare daily supplementation with haem iron versus ferrous sulphate on haemoglobin concentration and serum ferritin concentration after 12 weeks of supplementation.
Methods
This will be a two-arm, randomised controlled trial. Gambian children aged 6–12 months with anaemia will be recruited within a predefined geographical area and recruited by trained field workers. Eligible participants will be individually randomised using a 1:1 ratio within permuted blocks to daily supplementation for 12 weeks with either 10.0 mg of elemental iron as haem or ferrous sulphate. Safety outcomes such as diarrhoea and infection-related adverse events will be assessed daily by the clinical team (see Bah et al. Additional file 4_Adverse event eCRF). Linear regression will be used to analyse continuous outcomes, with log transformation to normalise residuals as needed. Binary outcomes will be analysed by binomial regression or logistic regression, Primary analysis will be by modified intention-to-treat (i.e., those randomised and who ingested at least one supplement dose of iron), with multiple imputations to replace missing data. Effect estimates will be adjusted for baseline covariates (C-reactive protein, alpha-1-acid glycoprotein, haemoglobin, ferritin, soluble transferrin receptor).
Discussion
This study will determine if therapeutic supplementation with haem iron is more efficacious than with conventional ferrous sulphate in enhancing haemoglobin and ferritin concentrations in anaemic children aged 6–12 months.
Trial registration
Pan African Clinical Trial Registry PACTR202210523178727
Journal Article
Daily iron supplementation does not impact on prevalence of exclusive breastfeeding or growth in young breastfed Gambian infants
2025
BackgroundIn a randomised placebo-controlled trial among exclusively breastfed rural Gambian infants aged 6–10 weeks at randomisation, daily iron supplementation for 14 weeks improved iron status. This secondary analysis explores the impact of iron supplementation on duration of exclusive breastfeeding and growth.MethodsBreastfed 6–10 week-old infants were supplemented for 14 weeks with either daily iron or placebo (n=101). Infant feeding practices were assessed weekly through questionnaires. Survival analysis was used to measure the effect of iron supplementation on age at and time to cessation of exclusive breastfeeding. Groups were also compared regarding the change in anthropometric z-scores between baseline and endline.ResultsAt endline, 31% (n=31/101) of infants were exclusively breastfed. There was no evidence that iron supplementation reduced the time to cessation of exclusive breastfeeding (median: 70 days (range: 7–105 days), iron: 67 days; placebo 71 days; Kaplan-Meier, log-rank test: p=0.15; Cox regression, crude HR: 1.42, 95% CI: 0.86 to 2.34, p=0.17; HR adjusting for infant age and sex: 1.40, 95% CI: 0.85 to 2.31, p=0.19) or age at cessation of exclusive breastfeeding (median time: 18 weeks (range:1–24 weeks), iron: 16 weeks; placebo 18 weeks; Kaplan-Meier, log-rank test: p=0.13; crude HR=1.47, 95% CI: 0.89, 2.43; p=0.13; HR adjusting for infant age and sex=1.44, 95% CI: 0.87, 2.39 p=0.16) There was no evidence that iron supplementation affected infant weight (p=0.79) or length (p=0.64) at endline or change in z-scores during the intervention period for weight-for-age (p=0.99), length-for-age (p=0.70) and weight-for-length (p=0.89). There was no evidence that duration of exclusive breastfeeding impacted endline anthropometric outcomes.ConclusionAlthough requiring replication in larger trials, these findings do not raise concerns about iron supplementations’ effect on feeding or growth in exclusively breastfed infants.
Journal Article
Antenatal iron supplementation and birth weight in conditions of high exposure to infectious diseases
by
Mwangi, Martin N.
,
Verhoef, Hans
,
Prentice, Andrew M.
in
Anaemia
,
Anemia
,
Anemia, Iron-Deficiency
2019
Background
A recent cohort study among Papua New Guinean women surprisingly showed iron deficiency during pregnancy to be associated with increased birth weight. These findings seemingly contradict previous trial evidence that iron supplementation leads to increased birth weight, particularly in iron-deficient women, and hence require explanation.
Main text
We have re-analysed data from a previous trial in Kenya and demonstrated that, because women who were initially iron deficient respond better to iron supplementation, they show an increase in birthweight. There is evidence that this benefit is decreased in iron-replete women, possibly due to the adverse effects of haemoconcentration that can impair oxygen and nutrient transfer across the placenta. The Papua New Guinean results might be explained by a similar differential response to the iron supplements that they all received.
Conclusions
Antenatal iron supplementation should ideally be administered in conjunction with measures to prevent, diagnose and treat malaria given the propensity of pathogenic microorganisms to proliferate in iron-supplemented individuals. However, even where services to prevent and treat malaria are poor, current evidence supports the conclusion that the benefits of universal iron supplementation outweigh its risks.
Please see related article:
https://bmcmedicine.biomedcentral.com/articles/10.1186/s12916-018-1146-z
.
Please see related article:
https://bmcmedicine.biomedcentral.com/articles/10.1186/s12916-019-1376-8
.
Journal Article
Micronutrient powders to combat anaemia in young children: do they work?
by
Teshome, Emily
,
Verhoef, Hans
,
Prentice, Andrew M.
in
Anaemia
,
Anemia - blood
,
Anemia, Iron-Deficiency - blood
2018
In 2016, the World Health Organization (WHO) recommended point-of-use fortification of complementary foods with iron-containing micronutrient powders to improve iron status and reduce anaemia in children at risk of anaemia. This recommendation continues to be debated. In a recent trial among Kenyan children aged 12–36 months, we found no evidence that daily point-of-use fortification was efficacious in improving haemoglobin concentration or plasma iron markers. An updated meta-analysis indicated that, on average, in an arbitrarily selected setting and with adherence as obtained under trial conditions, one may expect a small increase in haemoglobin concentration in preschool children, with the upper limit of the 95% CI virtually excluding an effect beyond 5.5 g/L. In the present paper, we elaborate on the interpretation of these findings and the meta-analyses that formed the basis for the WHO guidelines. In particular, we draw attention to the phenomenon that small group differences in the distribution of continuous outcomes (haemoglobin concentration, ferritin concentrations) can give a false impression of relatively large effects on the prevalence of the dichotomised outcomes (anaemia, iron deficiency).
Please see related articles:
https://bmcmedicine.biomedcentral.com/articles/10.1186/s12916-017-0839-z
,
https://bmcmedicine.biomedcentral.com/articles/10.1186/s12916-017-0867-8
Journal Article
Micronutrient Powders Combined With Malaria Chemoprevention to Improve Anaemia and Cognitive Function in Early Childhood in Mali: A Cluster‐Randomised Trial
2025
A cluster‐randomised controlled trial was conducted in 60 communities in southern Mali to evaluate the impact of micronutrient powders (MNP) combined with seasonal malaria chemoprevention (SMC) on anaemia (primary endpoint), Plasmodium infection, stunting and cognitive function in children < 5 years. The 60 communities were randomly allocated to the intervention or control arm, and cross‐sectional biomedical and cognitive surveys were conducted after 1 and 3 years in a random sample of 3 and 5 years olds (1052 and 1081 children, respectively). All children aged 3–59 m in intervention and control communities received two rounds of SMC each year during the peak malaria season, and in intervention communities, all children aged 6–59 m additionally received 4 months of daily MNP after the peak malaria season. Despite a high baseline prevalence of anaemia and good fidelity to intervention, this trial found no evidence of impact on study outcomes. The prevalence of anaemia was similar in both arms for both age groups after 1 and 3 years of intervention—after 3 years, the prevalence of anaemia amongst 3‐year olds was 57.6% in the intervention arm versus 60.1% in the control group (p = 0.352). For 5‐year olds, it was 51.3% and 53.0%, respectively (p = 0.607). No effect was observed on stunting or cognitive function either. Globally nearly 40% of children under 5 years old are anaemic, which affects their ability to grow and develop. A cluster randomised trial was conducted in 60 communities in Southern Mali to evaluate the added impact of home fortification with micronutrient powders, delivered alongside seasonal malaria chemoprevention, on anaemia, malaria infection, stunting and cognitive function in early childhood. Summary Around 60% of children under 5 years in Africa are anaemic due to iron deficiency and disease. Home fortification with micronutrient powders (MNP) and seasonal malaria chemoprevention (SMC) are recommended interventions to prevent anaemia and malaria. A cluster randomised trial in 60 rural communities in Southern Mali found that MNP, combined with SMC, had no impact on anaemia, stunting or cognitive development despite relatively high adherence and a high burden of anaemia and malaria. While MNP are effective in most contexts, they are not effective in every context. More research is needed to assess MNP's capacity to prevent anaemia in a wider range of settings—addressing both the biological mechanisms that might hinder absorption, as well as the sociocultural aspects for maximal utilisation.
Journal Article
Effects of an integrated poultry value chain, nutrition, gender and WASH intervention (SELEVER) on hygiene and child morbidity and anthropometry in Burkina Faso: A secondary outcome analysis of a cluster randomised trial
by
Pedehombga, Abdoulaye
,
Awonon, Josue
,
Ngure, Francis
in
Age groups
,
Agriculture
,
agriculture and nutrition
2023
Nutrition‐sensitive agriculture programmes have the potential to improve child nutrition outcomes, but livestock intensification may pose risks related to water, sanitation and hygiene (WASH) conditions. We assessed the impact of SELEVER, a nutrition‐ and gender‐sensitive poultry intervention, with and without added WASH focus, on hygiene practices, morbidity and anthropometric indices of nutrition in children aged 2−4 years in Burkina Faso. A 3‐year cluster randomised controlled trial was implemented in 120 villages in 60 communes (districts) supported by the SELEVER project. Communes were randomly assigned using restricted randomisation to one of three groups: (1) SELEVER intervention ( n = 446 households); (2) SELEVER plus WASH intervention ( n = 432 households); and (3) control without intervention ( n = 899 households). The study population included women aged 15−49 years with an index child aged 2−4 years. We assessed the effects 1.5‐years (WASH substudy) and 3‐years (endline) post‐intervention on child morbidity and child anthropometry secondary trial outcomes using mixed effects regression models. Participation in intervention activities was low in the SELEVER groups, ranging from 25% at 1.5 years and 10% at endline. At endline, households in the SELEVER groups had higher caregiver knowledge of WASH‐livestock risks (∆ = 0.10, 95% confidence interval [CI] [0.04−0.16]) and were more likely to keep children separated from poultry (∆ = 0.09, 95% CI [0.03−0.15]) than in the control group. No differences were found for other hygiene practices, child morbidity symptoms or anthropometry indicators. Integrating livestock WASH interventions alongside poultry and nutrition interventions can increase knowledge of livestock‐related risks and improve livestock‐hygiene‐related practices, yet may not be sufficient to improve the morbidity and nutritional status of young children. Few experimental studies have examined the potential nutritional benefits and health risks of livestock‐related interventions in low‐and middle‐income settings. We conducted a 3‐year cluster randomised trial of nutrition‐ and gender‐sensitive poultry intervention in Burkina Faso. Despite low participation in the intervention activities, caregiver's knowledge of water, sanitation and hygiene‐livestock risks was higher in the intervention groups than in the control group. No effects were found on hygiene and hygiene‐livestock‐related practices (except for practices involving separation between livestock and children) nor on child morbidity symptoms and anthropometry indicators.
Journal Article