Objective To provide a comprehensive and systematic analysis of demographic characteristics, clinical symptoms, laboratory findings and imaging features of coronavirus disease 2019 (COVID‐19) in pediatric patients. Methods A meta‐analysis was carried out to identify studies on COVID‐19 from December 25, 2019 to April 30, 2020. Results A total of 48 studies with 5829 pediatric patients were included. Children at all ages were at risk for COVID‐19. The main illness classification ranged as: 20% (95% CI: 14 to 26%, I 2 =91.4%) asymptomatic, 33% (95% CI: 23 to 43%, I 2 =95.6%) mild and 51% (95% CI: 42 to 61%, I 2 =93.4%) moderate. The typical clinical manifestations were fever 51% (95% CI: 45 to 57%, I 2 =78.9%) and cough 41% (95% CI: 35 to 47%, I 2 =81.0%). The common laboratory findings were normal white blood cell 69% (95% CI: 64 to 75%, I 2 =58.5%), lymphopenia 16% (95% CI: 11 to 21%, I 2 =76.9%) and elevated creatine‐kinase MB (CK‐MB) 37% (95% CI: 25 to 48%, I 2 =59.0%). The frequent imaging features were normal images 41% (95% CI: 30 to 52%, I 2 =93.4%) and ground‐glass opacity 36% (95% CI: 25 to 47%, I 2 =92.9%). Among children under 1‐year old, critical cases account for 14% (95% CI: 13 to 34%, I 2 =37.3%) that should be of concern. In addition, vomiting occurred in 33% (95% CI: 18 to 67%, I 2 =0.0%) cases that may also need attention. Conclusions Pediatric patients with COVID‐19 may experience milder illness with atypical clinical manifestations and rare lymphopenia. High incidence of critical illness and vomiting symptoms reward attention in children under 1‐year old. This article is protected by copyright. All rights reserved.

This paper presents a method to regulate the power transferred over a wireless link by adjusting the resonant operating frequency of the primary converter. A significant advantage of this method is that effective power regulation is maintained under variations in load, coupling and circuit parameters. This is particularly important when the wireless supply is used to power implanted medical devices where substantial coupling variations between internal and external systems is expected. The operating frequency is changed dynamically by altering the effective tuning capacitance through soft switched phase control. A thorough analysis of the proposed system has been undertaken, and experimental results verify its functionality.

There is a current outbreak of coronavirus disease 2019 (COVID-19), with a global spread. With the rapid increase in the number of infections, an increase is observed in the number of children with COVID-19. Most research findings are regarding adult cases, which are not always transferrable to children. Evidence-based studies are still expected to formulate clinical decisions for pediatric patients. In this review, we included 2597 pediatric patients that reported recently and evaluated the demographic, clinical, laboratory, and imaging features of children with COVID-19. We found that even lymphopenia was the most common lab finding in adults; it infrequently occurred in children (9.8%). Moreover, elevated creatine kinase MB isoenzyme was much more commonly observed in children (27.0%) than that in adults, suggesting that heart injury would be more likely to occur in pediatric patients. Our analysis may contribute to determine the spectrum of disease in children and to develop strategies to control the disease transmission.

Improvement of oil and protein concentrations is a primary breeding objective for canola (Brassica napus L.) grown in the low rainfall areas across southern Australia. This study investigates the relative influences of genotype and environment on the relationship between seed oil concentration and protein concentration of meal, and between seed components. The study also estimates the magnitude of genetic and genotype × environment variances in oil and protein concentrations in a set of interstate field evaluation experiments of genotypes with early and mid-season maturity conducted across southern Australia in 1996 and 1997.The oil concentration of seed ranged from 36 to 46% across maturity groups, locations, and years. The range of protein concentration of meal was 30–46%. Environment had a much larger impact than genotype on oil concentration of seed and protein concentration of meal. Several genotypes in this study had higher concentrations of oil in the seed and protein in the meal than the commercial cultivars used as controls. Significant (P < 0.05) genetic variance (σg2) and significant genotype × year × location interaction (σgyl2) was present in these 2 quality traits. However, the variance components for the interaction of genotype with location (σgl2) and with year (σgy2) were not significant (P > 0.05), indicating that ranking of genotypes remained constant across locations averaged over many years and across years averaged over many locations, respectively. A significant negative correlation (r�=�–0.73) between seed oil concentration and protein concentration of meal was observed across locations in 1997. Among the genotypes tested, there was no genetic correlation between these 2 traits, suggesting that seed oil concentration and protein concentration of meal can be increased simultaneously by selection. Increase in oil concentration of seed and protein concentration of meal was at the expense of seed residue.

BackgroundAs seed oil content (OC) is a key measure of rapeseed quality, better understanding the genetic basis of OC would greatly facilitate the breeding of high-oil cultivars. Here, we investigated the components of genetic effects and genotype × environment interactions (GE) that govern OC using a full diallel set of nine parents, which represented a wide range of the Chinese rapeseed cultivars and pure lines with various OCs.ResultsOur results from an embryo-cytoplasm-maternal (GoCGm) model for diploid seeds showed that OC was primarily determined by genetic effects (VG) and GE (VGE), which together accounted for 86.19% of the phenotypic variance (VP). GE (VGE) alone accounted for 51.68% of the total genetic variance, indicating the importance of GE interaction for OC. Furthermore, maternal variance explained 75.03% of the total genetic variance, embryo and cytoplasmic effects accounted for 21.02% and 3.95%, respectively. We also found that the OC of F1 seeds was mainly determined by maternal effect and slightly affected by xenia. Thus, the OC of rapeseed was simultaneously affected by various genetic components, including maternal, embryo, cytoplasm, xenia and GE effects. In addition, general combining ability (GCA), specific combining ability (SCA), and maternal variance had significant influence on OC. The lines H2 and H1 were good general combiners, suggesting that they would be the best parental candidates for OC improvement. Crosses H3 × M2 and H1 × M3 exhibited significant SCA, suggesting their potentials in hybrid development.ConclusionsOur study thoroughly investigated and reliably quantified various genetic factors associated with OC of rapeseed by using a full diallel and backcross and reciprocal backcross. This findings lay a foundation for future genetic studies of OC and provide guidance for breeding of high-oil rapeseed cultivars.

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BackgroundHerbicide tolerance is an important trait that allows effective weed management in wheat crops. Genetic knowledge of metribuzin tolerance in wheat is needed to develop new cultivars for the industry. Here, we evaluated metribuzin tolerance in a recombinant inbred line (RIL) mapping population derived from Synthetic W7984 and Opata 85 over two consecutive years to identify quantitative trait loci (QTL) contributing to the trait. Herbicide tolerance was measured by two chlorophyll traits, SPAD chlorophyll content index (CCI) and visual senescence score (SNS). The markers associated with major QTL from Synthetic W7984, positively contributing to reduced phytotoxic effects under herbicide treatment were validated in two F3/4 recombinant inbred populations developed from crosses of Synthetic W7984 × Westonia and Synthetic W7984 × Lang.ResultsComposite interval mapping (CIM) identified four QTL, two on chromosome 4A and one each on chromosomes 2D and 1A. The chromosomal position of the two QTL mapped on 4A within 10 cM intervals was refined and validated by multiple interval mapping (MIM). The major QTL affecting both measures of tolerance jointly explained 42 and 45% of the phenotypic variation by percentage CCI reduction and SNS, respectively. The identified QTL have a pure additive effect. The metribuzin tolerant allele of markers, Xgwm33 and Xbarc343, conferred lower phytotoxicity and explained the maximum phenotypic variation of 28.8 and 24.5%, respectively. The approximate physical localization of the QTL revealed the presence of five candidate genes (ribulose-bisphosphate carboxylase, oxidoreductase (rbcS), glycosyltransferase, serine/threonine-specific protein kinase and phosphotransferase) with a direct role in photosynthesis and/or metabolic detoxification pathways.ConclusionMetribuzin causes photo-inhibition by interrupting electron flow in PSII. Consequently, chlorophyll traits enabled the measure of high proportion of genetic variability in the mapping population. The validated molecular markers associated with metribuzin tolerance mediating QTL may be used in marker-assisted breeding to select metribuzin tolerant lines. Alternatively, validated favourable alleles could be introgressed into elite wheat cultivars to enhance metribuzin tolerance and improve grain yield in dryland farming for sustainable wheat production.Electronic supplementary materialThe online version of this article (10.1186/s12863-018-0690-z) contains supplementary material, which is available to authorized users.

This paper describes variation in the dynamics of seed softening (loss of impermeability) in 20 early-maturing genotypes, including 6 cultivars, of subterranean clover (Trifolium subterraneum L.). It reports the effect of 3 sites of seed production in south-western Australia on the pattern of softening in the first summer–autumn and on total softening over the subsequent 2 years. Seeds were softened at a single field location and in a diurnally fluctuating cabinet (60°C/15°C). There was significant variation among genotypes in the pattern of seed softening over the first 5 months after senescence. Cultivars Nungarin, Dwalganup, and Geraldton softened most rapidly in late February, whereas cultivars Dalkeith, Urana, and Izmir softened most rapidly in late March. The duration of field exposure required in order for 50% of the first season’s softening to occur ranged from 44 to 108 days among the 20 genotypes. Persistence of hard seeds into the second and third years also varied among genotypes. Of the cultivars, Nungarin and Izmir had the highest levels of residual hard seed after 30 months (5.3% and 3.9%, respectively), whereas Dalkeith had the lowest (0.9%). Site of seed production had a small but significant effect on both the pattern of softening in the first summer–autumn and the persistence of hard seeds in subsequent years. Seeds produced in a relatively high-rainfall site (768 mm of growing-season rainfall plus supplementary irrigation) had a slower rate of hard seed breakdown than those from either of 2 sites located in the wheatbelt (217 and 423 mm growing-season rainfall). Seed softening through exposure in the field and in a 60°C/15°C fluctuating-temperature cabinet was compared for all genotypes. The cabinet treatment was fairly successful in ranking genotypes for relative between-season hardseededness, although it underestimated total softening by an average of 16%. However, the cabinet treatment was a poor predictor of the within-season pattern of seed softening.