Genetically improved dual-purpose cowpea. Assessment of adoption and impact in the dry savannah of West Africa

The research reported here has the potential for contributing to a real improvement in the livelihoods of mixed crop-livestock farming households in the dry savannah zone of West Africa through widespread uptake of improved dual-purpose cowpea (IDPC). This technology offers opportunities for the production of more, higher-quality food for poor people and fodder for animals, along with soil-fertility improvement and other social benefits. The study examines issues surrounding the adoption and impact of the new varieties and associated management strategies. A novel approach was taken, combining GIS, a crop model, and household, community and participatory research approaches in northern Nigeria in order to address the following questions: `What types of impact are expected and their magnitude, where is the impact most likely to be felt, and by whom?'. The results suggest that the research investment has been beneficial, and the expected returns are high. Furthermore, the steps taken in order to quantify the benefits versus the costs of this research have identified for researchers, policy makers and development practitioners important considerations and possibilities for speeding up and widening the impact of this technology. First, it is a flexible technology that is appreciated by, and will have the greatest impact on, farming households that are usually poor and living in remoter areas where improved crop and livestock production are especially critical to livelihood strategies. Although the wealthiest households are more likely to be adopters, poorer households have also taken up IDPC. As it is the poorer households that cultivate 75% of the arable land, the potential impact of extending the technology to these more rural, less market-oriented households is huge. Uptake to date has been more likely to occur near wholesale markets in the most densely populated areas. Thus, finding innovative ways to increase access to markets and provide improved seeds and information for farmers in low-population density areas may have potentially large payoffs. The benefit from investment in rural market infrastructure and roads will be reflected in increased uptake of natural-resource-enhancing technologies such as IDPC. Farmer-impact workshops were held and the results pointed towards environmental- and poverty-impact indicators that can be monitored as people experiment with, and adapt, the new varieties and associated management techniques. The study has highlighted opportunities relating to the identification of the benefits of IDPC for livestock which are likely to emerge when data from several years of ongoing integrated crop-livestock trials become available. Given the population, climatic and land-use changes that are likely to occur in West Africa in the coming decades, there is an onus on researchers to streamline the effectiveness of R&D activities so that they benefit the rapidly increasing numbers of poor people in the region. The lessons learnt from the impact assessment study reported here will have much broader applicability in the future than to cowpea research alone. It is hoped that this analysis provides a research and impact-assessment strategy that will be useful for other crops and technologies, and in particular that it provides guidelines for assessments of more integrated natural resource management strategies (including livestock) and technologies. Most importantly, the novel multidisciplinary, multicentre and participatory approaches taken by the cowpea research team are helping to close the researcher-farmer feedback loop. Ultimately this is what will lead to faster and more widespread adoption and impact of new technologies

Second harmonic generation and birefringence of some ternary pnictide semiconductors

A first-principles study of the birefringence and the frequency dependent second harmonic generation (SHG) coefficients of the ternary pnictide semiconductors with formula ABC$_2$ (A = Zn, Cd; B = Si, Ge; C = As, P) with the chalcopyrite structures was carried out. We show that a simple empirical observation that a smaller value of the gap is correlated with larger value of SHG is qualitatively true. However, simple inverse power scaling laws between gaps and SHG were not found. Instead, the real value of the nonlinear response is a result of a very delicate balance between different intraband and interband terms.Comment: 13 pages, 12 figure

Machine learning algorithms performed no better than regression models for prognostication in traumatic brain injury

Objective: We aimed to explore the added value of common machine learning (ML) algorithms for prediction of outcome for moderate and severe traumatic brain injury. Study Design and Setting: We performed logistic regression (LR), lasso regression, and ridge regression with key baseline predictors in the IMPACT-II database (15 studies, n = 11,022). ML algorithms included support vector machines, random forests, gradient boosting machines, and artificial neural networks and were trained using the same predictors. To assess generalizability of predictions, we performed internal, internal-external, and external validation on the recent CENTER-TBI study (patients with Glasgow Coma Scale <13, n = 1,554). Both calibration (calibration slope/intercept) and discrimination (area under the curve) was quantified. Results: In the IMPACT-II database, 3,332/11,022 (30%) died and 5,233(48%) had unfavorable outcome (Glasgow Outcome Scale less than 4). In the CENTER-TBI study, 348/1,554(29%) died and 651(54%) had unfavorable outcome. Discrimination and calibration varied widely between the studies and less so between the studied algorithms. The mean area under the curve was 0.82 for mortality and 0.77 for unfavorable outcomes in the CENTER-TBI study. Conclusion: ML algorithms may not outperform traditional regression approaches in a low-dimensional setting for outcome prediction after moderate or severe traumatic brain injury. Similar to regression-based prediction models, ML algorithms should be rigorously validated to ensure applicability to new populations

Frequency of fatigue and its changes in the first 6 months after traumatic brain injury: results from the CENTER-TBI study

Background: Fatigue is one of the most commonly reported subjective symptoms following traumatic brain injury (TBI). The aims were to assess frequency of fatigue over the first 6 months after TBI, and examine whether fatigue changes could be predicted by demographic characteristics, injury severity and comorbidities. Methods: Patients with acute TBI admitted to 65 trauma centers were enrolled in the study Collaborative European NeuroTrauma Effectiveness Research in TBI (CENTER-TBI). Subj

Tracheal intubation in traumatic brain injury

Background: We aimed to study the associations between pre- and in-hospital tracheal intubation and outcomes in traumatic brain injury (TBI), and whether the association varied according to injury severity. Methods: Data from the international prospective pan-European cohort study, Collaborative European NeuroTrauma Effectiveness Research for TBI (CENTER-TBI), were used (n=4509). For prehospital intubation, we excluded self-presenters. For in-hospital intubation, patients whose tracheas were intubated on-scene were excluded. The association between intubation and outcome was analysed with ordinal regression with adjustment for the International Mission for Prognosis and Analysis of Clinical Trials in TBI variables and extracranial injury. We assessed whether the effect of intubation varied by injury severity by testing the added value of an interaction term with likelihood ratio tests. Results: In the prehospital analysis, 890/3736 (24%) patients had their tracheas intubated at scene. In the in-hospital analysis, 460/2930 (16%) patients had their tracheas intubated in the emergency department. There was no adjusted overall effect on functional outcome of prehospital intubation (odds ratio=1.01; 95% confidence interval, 0.79–1.28; P=0.96), and the adjusted overall effect of in-hospital intubation was not significant (odds ratio=0.86; 95% confidence interval, 0.65–1.13; P=0.28). However, prehospital intubation was associated with better functional outcome in patients with higher thorax and abdominal Abbreviated Injury Scale scores (P=0.009 and P=0.02, respectively), whereas in-hospital intubation was associated with better outcome in patients with lower Glasgow Coma Scale scores (P=0.01): in-hospital intubation was associated with better functional outcome in patients with Glasgow Coma Scale scores of 10 or lower. Conclusion: The benefits and harms of tracheal intubation should be carefully evaluated in patients with TBI to optimise benefit. This study suggests that extracranial injury should influence the decision in the prehospital setting, and level of consciousness in the in-hospital setting. Clinical trial registration: NCT02210221

Informed consent procedures in patients with an acute inability to provide informed consent

Purpose: Enrolling traumatic brain injury (TBI) patients with an inability to provide informed consent in research is challenging. Alternatives to patient consent are not sufficiently embedded in European and national legislation, which allows procedural variation and bias. We aimed to quantify variations in informed consent policy and practice. Methods: Variation was explored in the CENTER-TBI study. Policies were reported by using a questionnaire and national legislation. Data on used informed consent procedures were available for 4498 patients from 57 centres across 17 European countries. Results: Variation in the use of informed consent procedur