ORCID Profile
0000-0001-8780-069X
Current Organisation
Australian National University
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Publisher: Springer Science and Business Media LLC
Date: 23-06-2023
Abstract: A search for flavour-changing neutral current (FCNC) tqH interactions involving a top quark, another up-type quark ( q = u, c ), and a Standard Model (SM) Higgs boson decaying into a τ -lepton pair ( H → τ + τ − ) is presented. The search is based on a dataset of pp collisions at $$ \\sqrt{s} $$ s = 13 TeV that corresponds to an integrated luminosity of 139 fb − 1 recorded with the ATLAS detector at the Large Hadron Collider. Two processes are considered: single top quark FCNC production in association with a Higgs boson ( pp → tH ), and top quark pair production in which one of top quarks decays into Wb and the other decays into qH through the FCNC interactions. The search selects events with two hadronically decaying τ -lepton candidates ( τ had ) or at least one τ had with an additional lepton ( e , μ ), as well as multiple jets. Event kinematics is used to separate signal from the background through a multivariate discriminant. A slight excess of data is observed with a significance of 2.3 σ above the expected SM background, and 95% CL upper limits on the t → qH branching ratios are derived. The observed (expected) 95% CL upper limits set on the t → cH and t → uH branching ratios are $$ 9.4\\times {10}^{-4}\\left({4.8}_{-1.4}^{+2.2}\\times {10}^{-4}\\right) $$ 9.4 × 10 − 4 4.8 − 1.4 + 2.2 × 10 − 4 and $$ 6.9\\times {10}^{-4}\\left({3.5}_{-1.0}^{+1.5}\\times {10}^{-4}\\right) $$ 6.9 × 10 − 4 3.5 − 1.0 + 1.5 × 10 − 4 , respectively. The corresponding combined observed (expected) upper limits on the dimension-6 operator Wilson coefficients in the effective tqH couplings are C cϕ 1 . 35 (0 . 97) and C uϕ 1 . 16 (0 . 82).
Publisher: Wiley
Date: 18-03-2020
DOI: 10.1111/PBI.13363
Publisher: Springer Science and Business Media LLC
Date: 23-06-2023
Abstract: A search for light long-lived neutral particles with masses in the O (MeV–GeV) range is presented. The analysis targets the production of long-lived dark photons in the decay of a Higgs boson produced via gluon–gluon fusion or in association with a W boson. Events that contain displaced collimated Standard Model fermions reconstructed in the calorimeter or muon spectrometer are selected in 139 fb − 1 of $$ \\sqrt{s} $$ s = 13 TeV pp collision data collected by the ATLAS detector at the LHC. Background estimates for contributions from Standard Model processes and instrumental effects are extracted from data. The observed event yields are consistent with the expected background. Exclusion limits are reported on the production cross-section times branching fraction as a function of the mean proper decay length cτ of the dark photon, or as a function of the dark-photon mass and kinetic mixing parameter that quantifies the coupling between the Standard Model and potential hidden (dark) sectors. A Higgs boson branching fraction above 1% is excluded at 95% CL for a Higgs boson decaying into two dark photons for dark-photon mean proper decay lengths between 10 mm and 250 mm and dark photons with masses between 0.4 GeV and 2 GeV.
Publisher: Elsevier BV
Date: 11-2019
Publisher: Oxford University Press (OUP)
Date: 07-05-2020
DOI: 10.1093/PCP/PCAA062
Abstract: Alpha-linolenic acid (ALA, 18:3Δ9,12,15) and γ-linolenic acid \\ (GLA, 18:3Δ6,9,12) are important trienoic fatty acids, which are beneficial for human health in their own right, or as precursors for the biosynthesis of long-chain polyunsaturated fatty acids. ALA and GLA in seed oil are synthesized from linoleic acid (LA, 18:2Δ9,12) by the microsomal ω-3 fatty acid desaturase (FAD3) and Δ6 desaturase (D6D), respectively. Cotton (Gossypium hirsutum L.) seed oil composition was modified by transforming with an FAD3 gene from Brassica napus and a D6D gene from Echium plantagineum, resulting in approximately 30% ALA and 20% GLA, respectively. The total oil content in transgenic seeds remained unaltered relative to parental seeds. Despite the use of a seed-specific promoter for transgene expression, low levels of GLA and increased levels of ALA were found in non-seed cotton tissues. At low temperature, the germinating cottonseeds containing the linolenic acid isomers elongated faster than the untransformed controls. ALA-producing lines also showed higher photosynthetic rates at cooler temperature and better fiber quality compared to both untransformed controls and GLA-producing lines. The oxidative stability of the novel cottonseed oils was assessed, providing guidance for potential food, pharmaceutical and industrial applications of these oils.
Publisher: Springer Science and Business Media LLC
Date: 10-01-2015
Publisher: Elsevier BV
Date: 08-2023
Publisher: Springer Science and Business Media LLC
Date: 31-01-2019
Publisher: Wiley
Date: 21-02-2015
Abstract: Germplasm collections provide an extremely valuable resource for breeders and researchers. However, misclassification of accessions by species often hinders the effective use of these collections. We propose that use of high-throughput genotyping tools can provide a fast, efficient and cost-effective way of confirming species in germplasm collections, as well as providing valuable genetic ersity data. We genotyped 180 Brassicaceae s les sourced from the Australian Grains Genebank across the recently released Illumina Infinium Brassica 60K SNP array. Of these, 76 were provided on the basis of suspected misclassification and another 104 were sourced independently from the germplasm collection. Presence of the A- and C-genomes combined with principle components analysis clearly separated Brassica rapa, B. oleracea, B. napus, B. carinata and B. juncea s les into distinct species groups. Several lines were further validated using chromosome counts. Overall, 18% of s les (32/180) were misclassified on the basis of species. Within these 180 s les, 23/76 (30%) supplied on the basis of suspected misclassification were misclassified, and 9/105 (9%) of the s les randomly sourced from the Australian Grains Genebank were misclassified. Surprisingly, several in iduals were also found to be the product of interspecific hybridization events. The SNP (single nucleotide polymorphism) array proved effective at confirming species, and provided useful information related to genetic ersity. As similar genomic resources become available for different crops, high-throughput molecular genotyping will offer an efficient and cost-effective method to screen germplasm collections worldwide, facilitating more effective use of these valuable resources by breeders and researchers.
Publisher: CSIRO Publishing
Date: 2015
DOI: 10.1071/CP14269
Abstract: In this study, 137 canola (Brassica napus L.) accessions were evaluated for germination speed, which is a critical character in the plant life cycle. The accessions were grouped into three categories, fast (F), medium, and slow (S), with nine category F (7%) and 12 category S (9%) germination accessions identified and validated in repeated Petri dish and pot experiments. Although accessions in category F showed significantly faster germination and emergence than those in category S, seedling growth parameters did not differ greatly. Based on germination speed and seedling characteristics, four accessions with high early vigour and four with low early vigour were identified. Seed germination speed was not affected by seed weight and was not simply controlled by gibberellic acid and abscisic acid, but 10% smoke water significantly delayed seed germination. The identified accessions with contrasting early vigour can be used to study the genetic and molecular mechanism of seed germination and seedling development and to breed superior canola cultivars.
Publisher: Frontiers Media SA
Date: 27-11-2015
Publisher: Springer Science and Business Media LLC
Date: 20-06-2023
DOI: 10.1140/EPJC/S10052-023-11479-X
Abstract: A measurement of observables sensitive to effects of colour reconnection in top-quark pair-production events is presented using 139 $$\\hbox {fb}^{-1}$$ fb - 1 of 13 TeV proton–proton collision data collected by the ATLAS detector at the LHC. Events are selected by requiring exactly one isolated electron and one isolated muon with opposite charge and two or three jets, where exactly two jets are required to be b -tagged. For the selected events, measurements are presented for the charged-particle multiplicity, the scalar sum of the transverse momenta of the charged particles, and the same scalar sum in bins of charged-particle multiplicity. These observables are unfolded to the stable-particle level, thereby correcting for migration effects due to finite detector resolution, acceptance and efficiency effects. The particle-level measurements are compared with different colour reconnection models in Monte Carlo generators. These measurements disfavour some of the colour reconnection models and provide inputs to future optimisation of the parameters in Monte Carlo generators.
Publisher: CSIRO Publishing
Date: 2018
DOI: 10.1071/CP17392
Abstract: Soluble sugar content in silique wall and seeds of rapeseed (Brassica napus L.) has significant effects on seed oil formation and accumulation. We studied the relationship between soluble sugar content in B. napus seeds and silique wall and oil concentration under field conditions in two cropping seasons, and examined changes in soluble sugar content in seeds and silique wall under different nitrogen (N) levels. Two commercialised Chinese rapeseed varieties, HZ9 and HZ62, with high seed yield and different N responses were used. Our results indicated that carbon (C):N ratio and soluble sugar content in silique wall had the greater effect on seed oil concentration. When C:N ratio and soluble sugar content in silique wall were within 5–15% and 10–25%, respectively, plants had relatively well coordinated C and N metabolism, facilitating oil accumulation. During 25–35 days of silique development, when C:N ratio and soluble sugar content in silique wall were within 10–15 and 15–25%, respectively, oil synthesis was fastest the highest accumulation rate was 3.8% per day. When they were each & %, seeds tended to mature, and oil synthesis gradually decreased, ceased or degraded. During the early stage of silique development, if C:N ratio and soluble sugar content in silique wall were & % and 30%, there was no apparent tendency for oil accumulation, probably because of adverse environmental conditions. When N application increased from 0 to 270kg ha–1, final oil concentration in seeds decreased by 0.024%. In summary, C:N ratio and soluble sugar content in silique wall are important in regulating seed oil concentration, whereas excessive N application significantly reduced seed oil concentration. Therefore, appropriate reduction of N application would save resources, provide environment benefits and increase rapeseed oil production with no substantial reduction in seed yield, through coordinated seed yield and oil concentration.
Publisher: Elsevier BV
Date: 11-2020
Publisher: Wiley
Date: 13-04-2021
DOI: 10.1111/PPL.13390
Abstract: Nitrogen is an essential element for plant growth, and the relationship between leaf N content and photosynthesis has been widely studied in different species under steady‐state light. However, under natural conditions, the light intensity at the leaf level is always changing, inherently heterogeneous in time and space. Therefore, the effect of leaf N content on photosynthesis under dynamic light conditions needs further study. At present, the effects of leaf N content on leaf non‐steady‐state photosynthesis have not been reported in canola ( Brassica napus L.). To clarify the relationship between leaf N content and the speed of the response leaf gas exchange to variations in light intensity, eight genotypes of canola varying in leaf N content were used to study the temporal response of gas exchange to a step increase in irradiance. We found there were significant differences in non‐steady‐state photosynthesis, physiological characteristics, and anatomical traits across genotypes (the maximum litude was about fivefold), despite the lack of contrast under normal, steady‐state photosynthesis. In addition, initial stomatal conductance to water vapor in the darkness and leaf N content per leaf area were negatively correlated with the time required to achieve 50% and 100% of the maximum photosynthetic rate. Contrarily, the time required to reach 50% of the maximum stomatal conductance was positively correlated with the time required to achieve 90% of the maximum photosynthetic rate across genotypes. It is concluded that the genotypes of canola with higher N content per leaf area show a faster induction of photosynthesis to fluctuating light conditions.
Publisher: Elsevier BV
Date: 06-2018
DOI: 10.1016/J.PLANTSCI.2018.03.004
Abstract: To understand the influence of temperature on floral initiation and to reveal the relationship between floral bud development and yield potential of rapeseed (Brassica napus L.), early- ("1358"), intermediate- ("Zhongshuang No.11") and late- ("Zheshuang No.8") maturity genotypes were sown on different sowing dates under field conditions during four crop seasons. A multiplicative model was introduced to distinguish and quantify the effects of photoperiod and temperature on pre-floral initiation phase. Parameters in this model showed that early-maturity genotype was more sensitive to photoperiod while late-maturity genotype was more sensitive to vernalization. The relationships between cumulative temperature and mean temperature of pre-floral initiation phase could be well descried by exponential equation. The developmental rate of pre-floral initiation phase against mean daily temperature displayed an asymmetrical distribution, and it decreased rapidly when the mean temperature exceeded the optimum. Leaf primordia differentiated from the shoot apical meristem showed significant linear relationship with the thermal time at pre-floral initiation phase dynamic change of floral bud differentiated from the shoot apical meristem robustly fitted to a sigmoidal logistic curve. According to the fitted logistic equation, the maximum differentiation rate varied from 1.7 to 4.1 per 10 °Cd due to different sowing dates and genotypes. Averaged across growing seasons, sowing dates and genotypes, bud degeneration rate was 33% on the main raceme, and varied from 58% to 99% on the seven primary branches. The yield showed a significant correlation with floral bud number although the latter showed serious degeneration. In conclusion, the floral bud quantity largely determines rapeseed yield, and thus the genotypes with strong vernalization requirement should be planted early to extend the vegetative stage to achieve more fertile floral buds while the genotypes with weak vernalization requirement should be planted late to avoid flowering in chilling environment.
No related grants have been discovered for Jing Zhang.