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Incorporating the dominant male sterile gene, Ms44, in new maize varieties results in 50% non-pollen producing (FNP) varieties. This makes the varieties more nitrogen efficient and increases yield directly by an average of 200 kg ha−1 across yield levels. However, as half of the plants do not shed pollen, the presence of Ms44 in an FNP variety is clearly visible. This technology can improve food production and security in the African maize-based agri-food systems, but only if accepted by farmers. Farmers were therefore invited to 11 on-farm, researcher managed trial sites of FNP varieties in Kenya over 2 years. They were asked to identify the traits they find important in evaluating maize varieties and to score the FNP varieties, as well as their conventional counterparts, on these criteria (including yield, resistance to pests, and cob size) and overall, using a five-point hedonic scale. In total, 2,697 farmers participated, of which 62% were women. Farmers mentioned many traits they find important, especially yield and related traits, early maturity, and drought resistance, but also tassel and pollen formation. In 2017, mid-season, participants scored FNP varieties lower than conventional varieties on tassel and pollen formation, indicating that farmers could distinguish the trait. FNP varieties still received higher scores for yield and overall evaluation. In mid-season 2018, participants no longer scored FNP varieties lower for pollen formation as they now understood the technology. In both years, at the end-season evaluation, scores for tassel formation were not different, but participants scored FNP varieties higher for yield and overall. We conclude that farmers recognized the FNP trait but did not mind it as they clearly favored its yield advantage. The FNP technology, therefore, has high potential not only to increase maize yields, food production, and food security in the agricultural systems of Africa but also to increase varietal turnover and the adoption of new, high-yielding, climate-smart maize hybrids.
The search for life in the Universe is a fundamental problem of astrobiology and modern science. The current progress in the detection of terrestrial-type exoplanets has opened a new avenue in the characterization of exoplanetary atmospheres and in the search for biosignatures of life with the upcoming ground-based and space missions. To specify the conditions favourable for the origin, development and sustainment of life as we know it in other worlds, we need to understand the nature of global (astrospheric), and local (atmospheric and surface) environments of exoplanets in the habitable zones (HZs) around G-K-M dwarf stars including our young Sun. Global environment is formed by propagated disturbances from the planet-hosting stars in the form of stellar flares, coronal mass ejections, energetic particles and winds collectively known as astrospheric space weather. Its characterization will help in understanding how an exoplanetary ecosystem interacts with its host star, as well as in the specification of the physical, chemical and biochemical conditions that can create favourable and/or detrimental conditions for planetary climate and habitability along with evolution of planetary internal dynamics over geological timescales. A key linkage of (astro)physical, chemical and geological processes can only be understood in the framework of interdisciplinary studies with the incorporation of progress in heliophysics, astrophysics, planetary and Earth sciences. The assessment of the impacts of host stars on the climate and habitability of terrestrial (exo)planets will significantly expand the current definition of the HZ to the biogenic zone and provide new observational strategies for searching for signatures of life. The major goal of this paper is to describe and discuss the current status and recent progress in this interdisciplinary field in light of presentations and discussions during the NASA Nexus for Exoplanetary System Science funded workshop ‘Exoplanetary Space Weather, Climate and Habitability’ and to provide a new roadmap for the future development of the emerging field of exoplanetary science and astrobiology.
Malaria elimination is on global agendas following successful transmission reductions. Nevertheless moving from low to zero transmission is challenging. South Africa has an elimination target of 2018, which may or may not be realised in its hypoendemic areas.
The Agincourt Health and Demographic Surveillance System has monitored population health in north-eastern South Africa since 1992. Malaria deaths were analysed against individual factors, socioeconomic status, labour migration and weather over a 21-year period, eliciting trends over time and associations with covariates.
Of 13 251 registered deaths over 1.58 million person-years, 1.2% were attributed to malaria. Malaria mortality rates increased from 1992 to 2013, while mean daily maximum temperature rose by 1.5 °C. Travel to endemic Mozambique became easier, and malaria mortality increased in higher socioeconomic groups. Overall, malaria mortality was significantly associated with age, socioeconomic status, labour migration and employment, yearly rainfall and higher rainfall/temperature shortly before death.
Malaria persists as a small but important cause of death in this semi-rural South African population. Detailed longitudinal population data were crucial for these analyses. The findings highlight practical political, socioeconomic and environmental difficulties that may also be encountered elsewhere in moving from low-transmission scenarios to malaria elimination.
In multi-wheel undercarriages the application of the brakes not only affects the total load on the undercarriage, due to transference of some load to the nose wheel, but there is also a local transference between the wheels of the bogie itself. This note calculates these loads and gives two methods of preventing excessive overload of the tyres.
Cutan, a resistant non-hydrolyzable aliphatic biopolymer, was first reported in the cuticle of Agave americana and has generally been considered ubiquitous in leaf cuticles along with the structural biopolyester cutin. Because leaves and cuticles in the fossil record almost always have an aliphatic composition, it was argued that selective preservation of cutan played an important role in leaf preservation. However, the analysis of leaves using chemical degradation techniques involving hydrolysis to test for the presence of cutan reveals that it is absent in 16 of 19 taxa (angiosperm and gymnosperm), including many previously reported to contain cutan on the basis of pyrolysis data. Cutan is clearly much less widespread in leaves than previously thought, and its presence or absence does not exert any major bias on the preservation of leaves in the fossil record. In the absence of cutan, other constituents—cutin, plant waxes, and internal plant lipids—are incorporated into the geomacromolecule and contribute to the formation of a resistant aliphatic polymer by in situ polymerization during diagenesis.
Elucidating the cognitive architecture of schizophrenia promises to advance understanding of the clinical and biological substrates of the illness. Traditional cross-sectional neuropsychological approaches differentiate impaired from normal cognitive abilities but are limited in their ability to determine latent substructure. The current study examined the latent architecture of abnormal cognition in schizophrenia via a systematic approach.
Exploratory factor analysis (EFA) and confirmatory factor analysis (CFA) were carried out on a large neuropsychological dataset including the Brief Assessment of Cognition in Schizophrenia, Continuous Performance Test, Wisconsin Card Sorting Test, Benton Judgment of Line Orientation Test, and Wechsler Abbreviated Scale of Intelligence matrix reasoning derived from 1012 English-speaking ethnic Chinese healthy controls and 707 schizophrenia cases recruited from in- and out-patient clinics.
An initial six-factor model fit cognitive data in healthy and schizophrenia subjects. Further modeling, which accounted for methodological variance between tests, resulted in a three-factor model of executive functioning, vigilance/speed of processing and memory that appeared to best discriminate schizophrenia cases from controls. Factor analytic-derived g estimands and conventionally calculated g showed similar case–control discrimination. However, agreement analysis suggested systematic differences between both g indices.
Factor structures derived in the current study were broadly similar to those reported previously. However, factor structures between schizophrenia subjects and healthy controls were different. Roles of factor analytic-derived g estimands and conventional composite score g were further discussed. Cognitive structures underlying cognitive deficits in schizophrenia may prove useful for interrogating biological substrates and enriching effect sizes for subsequent work.
The heart of an inertial navigation system is the Inertial Measuring Unit (I.M.U.) as this carries out the fundamental tasks of measuring the vehicle acceleration and providing a spatial reference. The I.M.U. thus determines the system performance and accuracy; it also accounts for about two thirds of the initial cost of the system and is a major factor in the cost of ownership.
Up to now the majority of IN systems have used a stable platform I.M.U. where the gyros and accelerometers are mounted on a gimbal suspended platform which is servo controlled from the gyros. This has greatly eased the task of developing suitable gyros of the required accuracy, as the gimbal stabilization system isolates the gyros from the angular motion of the vehicle and greatly simplifies the subsequent computation in terms of axis transformations; it provides a direct read out of the euler angles—heading, pitch and roll. However such a system is inevitably mechanically complex and its ultimate reliability is constrained by such components as slip rings, servo motors, synchros, resolvers, encoders, gimbal bearings &c.
In the next decade there will be an increasing demand for more accurate self-contained navigation systems due to more stringent air traffic control requirements, particularly with the introduction of the supersonic transport. Although inertial systems have been fairly widely used in military aircraft and missiles, the only self-contained systems in service in civil aircraft are dead reckoning systems based on measuring the aircraft's velocity and heading and drift angle. A big improvement has been effected in the measurement of velocity and drift angle by the introduction of doppler radar. The accuracy achievable with doppler is not matched by the accuracy of existing heading reference systems and the overall accuracy is, at present, inadequate for future requirements.
An inertial navigation system is a possible alternative but its cost will be two to three times that of a doppler heading reference system.
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