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In recent years, unmanned aerial vehicle (UAV) technology has expanded to include UAV sprayers capable of applying pesticides. Very little research has been conducted to optimize application parameters and measure the potential of off-target movement from UAV-based pesticide applications. Field experiments were conducted in Raleigh, NC during spring 2018 to characterize the effect of different application speeds and nozzle types on target area coverage and uniformity of UAV applications. The highest coverage was achieved with an application speed of 1 m s−1 and ranged from 30% to 60%, whereas applications at 7 m s−1 yielded 13% to 22% coverage. Coverage consistently decreased as application speed increased across all nozzles, with extended-range flat-spray nozzles declining at a faster rate than air-induction nozzles, likely due to higher drift. Experiments measuring the drift potential of UAV-applied pesticides using extended-range flat spray, air-induction flat-spray, turbo air–induction flat-spray, and hollow-cone nozzles under 0, 2, 4, 7, and 9 m s−1 perpendicular wind conditions in the immediate 1.75 m above the target were conducted in the absence of natural wind. Off-target movement was observed under all perpendicular wind conditions with all nozzles tested but was nondetectable beyond 5 m away from the target. Coverage from all nozzles exhibited a concave-shaped curve in response to the increasing perpendicular wind speed due to turbulence. The maximum target coverage in drift studies was observed when the perpendicular wind was 0 and 8.94 m s−1, but higher turbulence at the two highest perpendicular wind speeds (6.71 and 8.94 m s−1) increased coverage variability, whereas the lowest variability was observed at 2.24 m s−1 wind speed. Results suggested that air-induction flat-spray and turbo air–induction flat-spray nozzles and an application speed of 3 m s−1 provided an adequate coverage of target areas while minimizing off-target movement risk.
The Turkana Basin of northwestern Kenya is well known for its rich Neogene–Quaternary vertebrate fossil record; however, it also represents one of the few locations in sub-Saharan Africa where Cretaceous vertebrate fossils, including dinosaurs and other archosaurs, are preserved. These Cretaceous deposits are colloquially referred to as the ‘Turkana Grits’, and assumed to be Cretaceous in age based on their limited biostratigraphy. The ‘Turkana Grits’ are overlain by Palaeogene volcanic rocks (<35 Ma), which are widely considered to record the earliest evidence of plume-related volcanism in the East African Rift System. In this study, we present the results of an integrated sedimentary provenance investigation of two units within the ‘Turkana Grits’ called the Lapur and Muruanachok sandstones. Analysis of U–Pb ages and Lu–Hf initial ɛHf(t) values from 1106 detrital zircons demonstrate that sediments are primarily derived from Neoarchaean and Neoproterozoic basement sources, except for six Palaeogene grains from the upper Lapur Sandstone, which are of unknown provenance. Considered together, these data point to the Mozambique Belt, which makes up the nearby rift flanks, as the primary provenance source. This is consistent with palaeocurrent data, and suggests localized sediment input by alluvial fans, which fed into NNW-directed fluvial systems. Perhaps the most surprising finding is the identification of the late Paleocene detrital zircons, which not only demonstrate that the depositional age for the top of the formation is Paleocene rather than Cretaceous, but also provides possible evidence for the oldest Palaeogene volcanic activity within the East African Rift System.
Hypertrophic cardiomyopathy has a range of clinical severity in children. Treatment options are limited, mainly on account of small patient size. Disopyramide is a sodium channel blocker with negative inotropic properties that effectively reduces left ventricular outflow tract gradients in adults with hypertrophic cardiomyopathy, but its efficacy in children is uncertain. A retrospective chart review of patients ⩽21 years of age with hypertrophic cardiomyopathy at our institution and treated with disopyramide was performed. Left ventricular outflow tract Doppler gradients before and after disopyramide initiation were compared as the primary outcome measure. Nine patients received disopyramide, with a median age of 5.6 years (range 6 days–12.9 years). The median left ventricular outflow tract Doppler gradient before initiation of disopyramide was 81 mmHg (range 30–132 mmHg); eight patients had post-initiation echocardiograms, in which the median lowest recorded Doppler gradient was 43 mmHg (range 15–100 mmHg), for a median % reduction of 58.2% (p=0.002). With median follow-up of 2.5 years, eight of nine patients were still alive, although disopyramide had been discontinued in six of the nine patients. Reasons for discontinuation included septal myomectomy (four patients), heart transplantation (one patient), and side effects (one patient). Disopyramide was effective for the relief of left ventricular outflow tract obstruction in children with hypertrophic cardiomyopathy, although longer-term data suggest that its efficacy is not sustained. In general, it was well tolerated. Further study in larger patient populations is warranted.
As a key indicator of childhood malnutrition, few studies have focused on stunting in relation to various socio-economic factors in which disadvantaged groups face in China. We conducted a community-based cross-sectional study incorporating forty-two rural counties in seven western provinces of China in 2011. In total, 5196 children aged 6–23 months were included. We used Poisson regression to examine risk factors for inadequate minimum dietary diversity (MDD) and stunting status, respectively. Overall, the proportion of children not meeting MDD was 44·5 %. Children aged 6–11 months (adjusted risk ratio (ARR)=1·39; 95 % CI 1·31, 1·49), with two siblings (ARR=1·09; 95 % CI 1·02, 1·17), delivered at home (ARR=1·30; 95 % CI 1·20, 1·41), within Yi (ARR=1·15; 95 % CI 1·04, 1·28) or Uighur groups (ARR=1·52; 95 % CI 1·36, 1·71), with an illiterate caregiver (ARR=2·12; 95 % CI 1·52, 2·96), receiving lowest income (ARR=1·32; 95 % CI 1·17, 1·50), and with breast-feeding in the last day (ARR=1·55; 95 % CI 1·44, 1·66) were more likely to have inadequate MDD. Moreover, inadequate MDD was positively associated with stunting (ARR=1·15; 95 % CI 1·01, 1·31). Other determinants for stunting were age, sex, place of delivery, minority group and income. The stunting prevalence and proportion of inadequate MDD remained high in Western China; to reduce stunting rates of ethnic minorities, further efforts addressing appropriate dietary feeding practices are needed, especially within these groups.
It is increasingly essential for medical researchers to be literate in statistics, but the requisite degree of literacy is not the same for every statistical competency in translational research. Statistical competency can range from ‘fundamental’ (necessary for all) to ‘specialized’ (necessary for only some). In this study, we determine the degree to which each competency is fundamental or specialized.
We surveyed members of 4 professional organizations, targeting doctorally trained biostatisticians and epidemiologists who taught statistics to medical research learners in the past 5 years. Respondents rated 24 educational competencies on a 5-point Likert scale anchored by ‘fundamental’ and ‘specialized.’
There were 112 responses. Nineteen of 24 competencies were fundamental. The competencies considered most fundamental were assessing sources of bias and variation (95%), recognizing one’s own limits with regard to statistics (93%), identifying the strengths, and limitations of study designs (93%). The least endorsed items were meta-analysis (34%) and stopping rules (18%).
We have identified the statistical competencies needed by all medical researchers. These competencies should be considered when designing statistical curricula for medical researchers and should inform which topics are taught in graduate programs and evidence-based medicine courses where learners need to read and understand the medical research literature.
We propose a novel explanation for the observed increase in the correlation of commodity prices over the past decade. In contrast to theories that rely on the increased influence of financial speculators, we examine the effect of interest rates on the volatility and correlation of commodity prices via a panel GARCH model. In theory, lower interest rates decrease the volatility of prices, as lower inventory costs promote the smoothing of transient shocks, and increase price correlation if common shocks are more persistent than idiosyncratic shocks. Empirically, we find that price volatility attributable to transitory shocks declines with interest rates, whereas particularly for metals prices, price correlation increases as interest rates decline.
This paper describes the system architecture of a newly constructed radio telescope – the Boolardy engineering test array, which is a prototype of the Australian square kilometre array pathfinder telescope. Phased array feed technology is used to form multiple simultaneous beams per antenna, providing astronomers with unprecedented survey speed. The test array described here is a six-antenna interferometer, fitted with prototype signal processing hardware capable of forming at least nine dual-polarisation beams simultaneously, allowing several square degrees to be imaged in a single pointed observation. The main purpose of the test array is to develop beamforming and wide-field calibration methods for use with the full telescope, but it will also be capable of limited early science demonstrations.
The modern concept of stress is commonly traced to the physiologist, Hans Selye. Selye viewed stress as a physiological response to a significant or unexpected change, describing a series of stages: alarm, resistance, and exhaustion, when an organism's adaptive mechanisms finally failed. While Selye originally focused on nonspecific physiological responses to harmful agents, the stress concept has since been used to examine the relationship between a variety of environmental stressors and mental disorders and chronic organic diseases such as hypertension, gastric ulcers, arthritis, allergies, and cancer. This edited volume brings together leading scholars to explore the emergence and development of the stress concept and its ever-changing definitions. It examines how the concept has been used to connect disciplines such as ecology, physiology, psychology, psychiatry, public health, urban planning, architecture, and a range of social sciences; its application in a variety of sites such as the battlefield, workplace, clinic, hospital, and home; and the emergence of techniques of stress management in a variety of different socio-cultural and scientific locations. Contributors: Theodore M. Brown, David Cantor, Otniel E. Dror, Rhodri Hayward, Mark Jackson, Robert G. W. Kirk, Junko Kitanaka, Tulley Long, Joseph Melling, Edmund Ramsden, Elizabeth Siegel Watkins, Allan Young. David Cantor is Acting Director, Office of History, National Institutes of Health. Edmund Ramsden is Research Fellow at the Centre for History of Science, Technology and Medicine, University of Manchester.
David Cantor, Acting Director, Office of History, National Institutes of Health,Edmund Ramsden, Research Fellow at the Centre for History of Science, Technology and Medicine, University of Manchester