Browsing by Author "Li L"
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- ItemDifferent effects of grazing and nitrogen addition on ecosystem multifunctionality are driven by changes in plant resource stoichiometry in a typical steppe(2022-08-05) Li L; He XZ; Zhang X; Hu J; Wang M; Wang Z; Hou FPurpose: Herbivore grazing and nitrogen (N) input may alter the multiple ecosystem functions (i.e., multifunctionality, hereafter) associated with carbon (C), N, and phosphorus (P) cycling. Most studies on variations in plant diversity, soil biotic or abiotic factors, and linkages to ecosystem functions have focused on grazing or N enrichment alone. Few studies have combined these two factors to explore the role of plant resource stoichiometry (C:N:P ratios) in ecosystem multifunctionality (EMF) control. Here, we evaluated the direct and indirect effects of stocking rate (0, 2.7, 5.3, and 8.7 sheep ha− 1) and N addition rate (0, 5, 10, and 20 g N m− 2 yr− 1) on a range of ecosystem functions and EMF via changing plant diversity, soil pH and plant resource stoichiometry in a typical steppe on the Loess Plateau. Results: We found that increasing stocking rate and interaction between grazing and N addition significantly decreased EMF, while increasing N addition rate significantly promoted EMF. Grazing decreased soil NH4+-N, soil NO3−-N, aboveground biomass, and plant C, N, and P pools, but increased soil total N and P at 8.7 and 5.3 sheep ha− 1, respectively. N addition increased soil NH4+-N, NO3−-N, and total P. Plant aboveground biomass, and plant C, N, and P pools increased at the lower N addition rate (≤ 5 g N m− 2 yr− 1) under grazing. The structural equation models indicated that (1) EMF was driven by the direct effects of grazing and the indirect effects of grazing on plant resource stoichiometry and soil pH; (2) EMF increased with increasing N addition rates, but such positive response of EMF to increasing N addition rates was alleviated at high levels of plant resource stoichiometry and diversity; and (3) the indirect effects of plant diversity induced by grazing and N addition had moderate effects on EMF via the variations of plant resource stoichiometry. Conclusions: This study demonstrated grazing and N addition had contrasting effects on ecosystem multifunctionality in a typical steppe, and highlighted the capacity of plant diversity in balancing plant elements that serve as a key mechanism in the maintenance of EMF in response to intensive grazing and N enrichment.
- ItemFunctional response and prey stage preference of Neoseiulus barkeri on Trasonemus confuses(Systematic and Applied Acarology Society London, 2018-11-23) Li L; Jiao R; Lichen Y; He XZ; He L; Xu C; Zhang L; Liu J
- ItemNon-negative Matrix Factorization: A Survey(Oxford University Press on behalf of the British Computer Society, 2021-07-01) Gan J; Liu T; Li L; Zhang JNon-negative matrix factorization (NMF) is a powerful tool for data science researchers, and it has been successfully applied to data mining and machine learning community, due to its advantages such as simple form, good interpretability and less storage space. In this paper, we give a detailed survey on existing NMF methods, including a comprehensive analysis of their design principles, characteristics and drawbacks. In addition, we also discuss various variants of NMF methods and analyse properties and applications of these variants. Finally, we evaluate the performance of nine NMF methods through numerical experiments, and the results show that NMF methods perform well in clustering tasks.
- ItemOrigin and evolution of the kiwifruit canker pandemic(Oxford University Press, 2017-04-01) McCann HC; Li L; Liu Y; Li D; Pan H; Zhong C; Rikkerink EHA; Templeton MD; Straub C; Colombi E; Rainey PB; Huang HRecurring epidemics of kiwifruit (Actinidia spp.) bleeding canker disease are caused by Pseudomonas syringae pv. actinidiae (Psa). In order to strengthen understanding of population structure, phylogeography and evolutionary dynamics, we isolated Pseudomonas from cultivated and wild kiwifruit across six provinces in China. Based on the analysis of eighty sequenced Psa genomes we show that China is the origin of the pandemic lineage but that strain diversity in China is confined to just a single clade. In contrast, Korea and Japan harbour strains from multiple clades. Distinct independent transmission events marked introduction of the pandemic lineage into New Zealand, Chile, Europe, Korea and Japan. Despite high similarity within the core genome and minimal impact of within-clade recombination, we observed extensive variation even within the single clade from which the global pandemic arose.
- ItemParameter-Free Extreme Learning Machine for Imbalanced Classification Authors Li, L - China Agric(Springer Science+Business Media, LLC, 2020-12) Li L; Zhao K; Sun R; Gan J; Yuan G; Liu TImbalanced data distribution is a common problem in classification situations, that is the number of samples in different categories varies greatly, thus increasing the classification difficulty. Although many methods have been used for the imbalanced data classification, there are still problems with low classification accuracy in minority class and adding additional parameter settings. In order to increase minority classification accuracy in imbalanced problem, this paper proposes a parameter-free weighting learning mechanism based on extreme learning machine and sample loss values to balance the number of samples in each training step. The proposed method mainly includes two aspects: the sample weight learning process based on the sample losses; the sample selection process and weight update process according to the constraint function and iterations. Experimental results on twelve datasets from the KEEL repository show that the proposed method could achieve more balanced and accurate results than other compared methods in this work.
- ItemTemperature‑dependent development and reproduction of Tarsonemus confusus (Acari: Tarsonemidae): an important pest mite of horticulture(Springer, 2022-11-17) Li L; Yu L; He L; He XZ; Jiao R; Xu CThe tarsonemid mite Tarsonemus confusus Ewing has become an economically important pest in orchards in China. This study investigated the temperature-dependent development and reproduction of T. confusus at 15, 20, 25, 30, 33 and 35 °C. Eggs failed to hatch at 35 °C. When temperature increased from 15 to 30 °C, the developmental rate of eggs, larvae and quiescent larvae and that from egg to adulthood of both sexes significantly increased, and the time period required by females to commence oviposition significantly decreased. The lower temperature threshold (T0) for the development of eggs, larvae and quiescent larvae was between 9.3 and 12.0 °C and both sexes required about 60 degree days (DD) to complete a life cycle. Females were expected to start oviposition at 12.9 °C. The number of eggs laid, the number of female offspring produced and the egg hatch rate were significantly higher at 20, 25 and 30 °C than at 15 and 33 °C. Increasing temperature shortened the longevity of both sexes but increased the intrinsic rate of increase (rm) and finite capacity for increase (λ) with significantly shorter generation time (T) and doubling time (DT) within a temperature range of 15-30 °C. The net reproductive rate (R0) was highest at 25 °C. Results of this study may improve our knowledge of fundamental biology and ecology in genus Tarsonemus in general and in T. confusus in particular. Based on the local climate conditions, the applications of these results in predicting the seasonal population dynamics of T. confusus and timing the pest management are discussed.
- ItemUsing Observational Data to Estimate the Effect of Hand Washing and Clean Delivery Kit Use by Birth Attendants on Maternal Deaths after Home Deliveries in Rural Bangladesh, India and Nepal.(2015) Seward N; Prost A; Copas A; Corbin M; Li L; Colbourn T; Osrin D; Neuman M; Azad K; Kuddus A; Nair N; Tripathy P; Manandhar D; Costello A; Cortina-Borja MBACKGROUND: Globally, puerperal sepsis accounts for an estimated 8-12% of maternal deaths, but evidence is lacking on the extent to which clean delivery practices could improve maternal survival. We used data from the control arms of four cluster-randomised controlled trials conducted in rural India, Bangladesh and Nepal, to examine associations between clean delivery kit use and hand washing by the birth attendant with maternal mortality among home deliveries. METHODS: We tested associations between clean delivery practices and maternal deaths, using a pooled dataset for 40,602 home births across sites in the three countries. Cross-sectional data were analysed by fitting logistic regression models with and without multiple imputation, and confounders were selected a priori using causal directed acyclic graphs. The robustness of estimates was investigated through sensitivity analyses. RESULTS: Hand washing was associated with a 49% reduction in the odds of maternal mortality after adjusting for confounding factors (adjusted odds ratio (AOR) 0.51, 95% CI 0.28-0.93). The sensitivity analysis testing the missing at random assumption for the multiple imputation, as well as the sensitivity analysis accounting for possible misclassification bias in the use of clean delivery practices, indicated that the association between hand washing and maternal death had been over estimated. Clean delivery kit use was not associated with a maternal death (AOR 1.26, 95% CI 0.62-2.56). CONCLUSIONS: Our evidence suggests that hand washing in delivery is critical for maternal survival among home deliveries in rural South Asia, although the exact magnitude of this effect is uncertain due to inherent biases associated with observational data from low resource settings. Our findings indicating kit use does not improve maternal survival, suggests that the soap is not being used in all instances that kit use is being reported.