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Potential effectiveness of harvest weed seed control (HWSC) systems depends upon seed shatter of the target weed species at crop maturity, enabling its collection and processing at crop harvest. However, seed retention likely is influenced by agroecological and environmental factors. In 2016 and 2017, we assessed seed-shatter phenology in 13 economically important broadleaf weed species in soybean [Glycine max (L.) Merr.] from crop physiological maturity to 4 wk after physiological maturity at multiple sites spread across 14 states in the southern, northern, and mid-Atlantic United States. Greater proportions of seeds were retained by weeds in southern latitudes and shatter rate increased at northern latitudes. Amaranthus spp. seed shatter was low (0% to 2%), whereas shatter varied widely in common ragweed (Ambrosia artemisiifolia L.) (2% to 90%) over the weeks following soybean physiological maturity. Overall, the broadleaf species studied shattered less than 10% of their seeds by soybean harvest. Our results suggest that some of the broadleaf species with greater seed retention rates in the weeks following soybean physiological maturity may be good candidates for HWSC.
Seed shatter is an important weediness trait on which the efficacy of harvest weed seed control (HWSC) depends. The level of seed shatter in a species is likely influenced by agroecological and environmental factors. In 2016 and 2017, we assessed seed shatter of eight economically important grass weed species in soybean [Glycine max (L.) Merr.] from crop physiological maturity to 4 wk after maturity at multiple sites spread across 11 states in the southern, northern, and mid-Atlantic United States. From soybean maturity to 4 wk after maturity, cumulative percent seed shatter was lowest in the southern U.S. regions and increased moving north through the states. At soybean maturity, the percent of seed shatter ranged from 1% to 70%. That range had shifted to 5% to 100% (mean: 42%) by 25 d after soybean maturity. There were considerable differences in seed-shatter onset and rate of progression between sites and years in some species that could impact their susceptibility to HWSC. Our results suggest that many summer annual grass species are likely not ideal candidates for HWSC, although HWSC could substantially reduce their seed output during certain years.
Over the past decade in the Netherlands, most operators have only developed a single doublet. The learning effect from these single events is suboptimal, and operators have only been capable of developing doublets in areas with relatively low exploration risk. This ‘stand-alone’ approach can be significantly improved by a collective approach to derisk regions with similar subsurface characteristics. Such a play-based portfolio approach, which is common in the oil and gas industry, can help to accelerate the development of the geothermal industry through unlocking resource potential in areas marked by high upfront geological risk, effectively helping reduce costs for the development. The basis of the methodology is to deploy new information to the play portfolio by trading off with the risk of the first wells, resulting in a strong geological risk reduction.
The added value of the portfolio approach is demonstrated for the Netherlands in this paper through a comparison with a ‘stand-alone’ development. In the stand-alone approach, each new project will be equally risky, and therefore relatively unprofitable. In the case of a portfolio approach, all experience about the play is used optimally for derisking. In case of success, subsequent projects will have a higher chance of being successful, due to the experience gained in previous projects. Even if a project fails, this may help in increasing the probability of success for subsequent projects. For plays that are initially considered too risky for the market to start developing, the value of information (VoI) of a play-based portfolio approach will help by derisking the play to such an extent that it becomes attractive for the market to develop, even at high initial risk. It can be demonstrated for several geothermal plays in the Netherlands that by adopting the portfolio approach, the probability of a play being developed becomes higher, the number of successfully developed projects increases and the average profitability of the project will also be higher. Five more advantages are: (1) continuous improvement by integrated project development, (2) cost reduction through synergy, efficiency and standardisation, (3) optimisation of the surface heat demand and infrastructure, (4) the possibility of structural research and development (R&D) and innovation, and (5) financing advantages. The advantages reinforce each other.
A preliminary estimate of the geothermal potential of the Netherlands adopting the portfolio approach is between 90 and 275 Petajoules (PJ). For about 350 doublets being developed, producing about 70 PJ, the value of the advantage of the play-based portfolio approach is €2 billion for the three main plays: Rotliegend, Triassic and Jurassic/Cretaceous. The learning effects of synergy, efficiency and standardisation are expected to be significant.
To determine clinically meaningful subgroups of persons with traumatic brain injury (TBI) who have failed performance validity testing.
Study participants were selected from a cohort of 674 participants with definitive medical evidence of TBI. Participants were those who failed performance validity testing (the Word Memory Test, using the standard cutoffs). Participants were administered cognitive tests and self-report questionnaires. Test and questionnaire results were summarized as 12 dimension scores. Cluster analysis using the k-means method was performed.
Cluster analysis for the 143 retained participants indicated three subgroups. These subgroups differed on patterns of scores. Subgroup 1 was impaired for memory and had no excessive complaints. Subgroup 2 had impaired memory and processing speed as well as concern regarding cognition function. Subgroup 3 showed impairment on all cognitive tests and excess complaints in multiple areas.
These results provide a preliminary basis for improved understanding of poor performance validity.
Scholarly analyses of the South African hashtag campus movements of 2015–2016, #RhodesMustFall and #FeesMustFall, have evaluated them in terms of their success in bringing about political change in a linear causal fashion. Through a reading of Thando Mgqolozana’s novel, Unimportance (2014), the history of the University of the Western Cape, as well as scholarly commentary on #RMF and #FMF, this article argues that an attention to the cyclicality of time as it unfolds within the space of the university is crucial for properly understanding the events of 2015–2016.
To analyse the effect of community-based counselling on feeding patterns during the first 12 weeks after birth, and to study whether the effect differs by maternal HIV status, educational level or household wealth.
Cluster-randomized trial with fifteen clusters in each arm to evaluate an integrated package providing two pregnancy and five postnatal home visits delivered by community health workers. Infant feeding data were collected using 24 h recall of nineteen food and fluid items.
A township near Durban, South Africa.
Pregnant women (1894 intervention and 2243 control) aged 17 years or more.
Twelve weeks after birth, 1629 (intervention) and 1865 (control) mother–infant pairs were available for analysis. Socio-economic conditions differed slightly across intervention groups, which were considered in the analyses. There was no effect on early initiation of breast-feeding. At 12 weeks of age the intervention doubled exclusive breast-feeding (OR=2·29; 95 % CI 1·80, 2·92), increased exclusive formula-feeding (OR=1·70; 95 % CI 1·28, 2·27), increased predominant breast-feeding (OR=1·71; 95 % CI 1·34, 2·19), decreased mixed formula-feeding (OR=0·68; 95 % CI 0·55, 0·83) and decreased mixed breast-feeding (OR=0·54; 95 % CI 0·44, 0·67). The effect on exclusive breast-feeding at 12 weeks was stronger among HIV-negative mothers than HIV-positive mothers (P=0·01), while the effect on mixed formula-feeding was significant only among HIV-positive mothers (P=0·03). The effect on exclusive feeding was not different by household wealth or maternal education levels.
A perinatal intervention package delivered by community health workers was effective in increasing exclusive breast-feeding, exclusive formula-feeding and decreasing mixed feeding.
To outline a framework and a process for assessing the needs for capacity development to achieve nutrition objectives, particularly those targeting maternal and child undernutrition.
Commentary and conceptual framework.
Low- and middle-income countries.
A global movement to invest in a package of essential nutrition interventions to reduce maternal and child undernutrition in low- and middle-income countries is building momentum. Capacity to act in nutrition is known to be minimal in most low- and middle-income countries, and there is a need for conceptual clarity about capacity development as a strategic construct and the processes required to realise the ability to achieve population nutrition and health objectives. The framework for nutrition capacity development proposed recognises capacity to be determined by a range of factors across at least four levels, including system, organisational, workforce and community levels. This framework provides a scaffolding to guide systematic assessment of capacity development needs which serves to inform strategic planning for capacity development.
Capacity development is a critical prerequisite for achieving nutrition and health objectives, but is currently constrained by ambiguous and superficial conceptualisations of what capacity development involves and how it can be realised. The current paper provides a framework to assist this conceptualisation, encourage debate and ongoing refinement, and progress capacity development efforts.
Skill-biased technical change occupied empirical economists for much of the 1990s. The empirical literature firmly established a positive correlation between technology indicators and demand shifts. In the minds of many, that has established a causal relationship. This leap of faith, however, is at odds with Hicks's conventional wisdom that endogenous technological change will be biased toward using cheap and abundant resources. In addition, if the rate of technical change is considered to be endogenous, the assumption of an exogenous bias toward skilled labor should at least be questioned. Two hypotheses explaining endogenous skill bias in technical change have been suggested in the theoretical literature: the acceleration effect and the market size effect. In this paper these are studied in a single endogenous-growth model to derive the sufficient and necessary conditions for both hypotheses. After confronting these conditions with the evidence, the paper concludes that it strongly favors the acceleration hypothesis.
Recent studies have claimed the existence of very massive stars (VMS) up to 300 M⊙ in the local Universe. As this finding may represent a paradigm shift for the canonical stellar upper-mass limit of 150 M⊙, it is timely to discuss the status of the data, as well as the far-reaching implications of such objects. We held a Joint Discussion at the General Assembly in Beijing to discuss (i) the determination of the current masses of the most massive stars, (ii) the formation of VMS, (iii) their mass loss, and (iv) their evolution and final fate. The prime aim was to reach broad consensus between observers and theorists on how to identify and quantify the dominant physical processes.
Though sadly understudied, the postbellum, pre-New Negro era of African American poetry, roughly 1865 to the First World War, looms as a pivotal if not defining moment in the larger sweep of African American poetics and culture. Perhaps one of the reasons for this era's neglect is that prominent Harlem Renaissance poets – James Weldon Johnson and Sterling A. Brown in particular – went to considerable lengths to distance themselves and their generation from the previous one and its alleged political and artistic shortcomings. For them, both the dialect and genteel (or romantic) traditions of African American poetry held little promise for their own artistic projects and seemed to wilt under the pressure of deteriorating racial conditions. Yet New Negro poets confronted many of the same dilemmas, and indeed pursued many of the same agendas as their forebears, suggesting a closer relationship – even indebtedness – that was seldom acknowledged. Perhaps it is this deeply conflicted relationship with the postbellum generation that begins to suggest the era's enduring significance.
Acknowledged or not, the postbellum generation created precedents for negotiating American popular culture and its racial politics, for addressing “mainstream” audiences and tastes shaped by popular culture, and for working within received poetic traditions. In a sense, this generation prefigured modernist poetics by confronting the conundrum of simultaneous insider and outsider status. They were the first to market to a mainstream or popular taste, while attempting to address the needs and expectations of blacks at a particularly dire moment in American racial history.