时间差分算法(Temporal difference methods,TD)是一类模型无关的强化学习算法.该算法拥有较低的方差和可以在线(On-line)学习的优点,得到了广泛的应用.但对于一种给定的TD算法,往往只能通过调整步长参数或其他超参数来加速收敛,这也就...时间差分算法(Temporal difference methods,TD)是一类模型无关的强化学习算法.该算法拥有较低的方差和可以在线(On-line)学习的优点,得到了广泛的应用.但对于一种给定的TD算法,往往只能通过调整步长参数或其他超参数来加速收敛,这也就造成了加速TD算法收敛的方法匮乏.针对此问题提出了一种利用蒙特卡洛算法(Monte Carlo methods,MC)来加速TD算法收敛的方法(Accelerate TD by MC,ATDMC).该方法不仅可以适用于绝大部分的TD算法,而且不需要改变在线学习的方式.为了证明方法的有效性,分别在同策略(On-policy)评估、异策略(Off-policy)评估和控制(Control)三个方面进行了实验.实验结果表明ATDMC方法可以有效地加速各类TD算法.展开更多
Identification and counting of rice light-trap pests are important to monitor rice pest population dynamics and make pest forecast. Identification and counting of rice light-trap pests manually is time-consuming, and ...Identification and counting of rice light-trap pests are important to monitor rice pest population dynamics and make pest forecast. Identification and counting of rice light-trap pests manually is time-consuming, and leads to fatigue and an increase in the error rate. A rice light-trap insect imaging system is developed to automate rice pest identification. This system can capture the top and bottom images of each insect by two cameras to obtain more image features. A method is proposed for removing the background by color difference of two images with pests and non-pests. 156 features including color, shape and texture features of each pest are extracted into an support vector machine （SVM） classifier with radial basis kernel function. The seven-fold cross-validation is used to improve the accurate rate of pest identification. Four species of Lepidoptera rice pests are tested and achieved 97.5% average accurate rate.展开更多
The sclerotia of Villosiclava virens were found commonly in high altitude and the temperate regions, where the temperatures are relatively low in rice filling stage. To make sure if low temperature induce the scleroti...The sclerotia of Villosiclava virens were found commonly in high altitude and the temperate regions, where the temperatures are relatively low in rice filling stage. To make sure if low temperature induce the sclerotial formation in V. virens, the inoculated rice panicles in laboratory and the diseased rice panicles cut from paddy fields were treated under different temperatures. The results showed that 3 days of night temperature at 15°C were enough to induce the sclerotial formation. The low temperature was much more effective for young balls with intact membranes. After appearance of chlamydospores on the ball surfaces, the sclerotium could not differentiate anymore. The sclerotia began to differentiate below the chlamydospore layer and gradually grew onto the ball surfaces. This suggests that low temperature in the early development stage of false smut balls is an important factor to induce the sclerotial differentiation, and rice cultivars with long growth periods are able to produce more sclerotium-bearing balls, which will produce mass of spores in paddy field in the coming year.展开更多
The complete nucleotide sequence of an isolate of Citrus vein enation virus（CVEV-XZG） from China has been determined for the first time. The genome consisted of 5 983 nucleotides, coding for five open reading frames...The complete nucleotide sequence of an isolate of Citrus vein enation virus（CVEV-XZG） from China has been determined for the first time. The genome consisted of 5 983 nucleotides, coding for five open reading frames（ORFs）, had a similar genomic organization features with Pea enation mosaic virus（PEMV）. Nucleotide and deduced amino acid sequence identity of the five ORFs compared to isolate CVEV VE-1 range from 97.1 to 99.0% and 97.4 to 100.0%, these values compared to isolate PEMV-1 range from 45.2 to 51.6% and 31.1 to 45.2%. Phylogenetic analysis based on the complete genome sequence showed that the isolate CVEV-XZG had close relationship with Pea enation mosaic virus. The results supports CVEV may be a new member of genus Enamovirus. The full sequence of CVEV-XZG presented here may serve as a basis for future study of CVEV in China.展开更多
Rice false smut is caused by ascomycete Villosiclava virens, whose potential alternative hosts have been assumed previ- ously. Here its potential alternative hosts were surveyed and identified from 2008 to 2013 in the...Rice false smut is caused by ascomycete Villosiclava virens, whose potential alternative hosts have been assumed previ- ously. Here its potential alternative hosts were surveyed and identified from 2008 to 2013 in the main rice-growing regions in China. Two common weeds in paddy fields, Digitaria sanguinalis Scop. and Echinochloa crusgalli （L.） Beauv., were found to present the similar symptoms to smut diseases in a few individuals in 2012 and 2013 in Zhejiang and Sichuan provinces of China, respectively. After the examinations of the spore morphology, their infection and extension mode in hosts, pathogen cell wall components, and molecular identification, the two pathogens were identified to be the Basidiomycetes, Ustilago syntherismae and Ustilago trichophora, respectively. So far there has been no alternative host of V. virens to be identified in China. These suggest that the alternative hosts of V. virens, if they do exist, are not possible to play an important role in the pathogen life cycle and the disease epidemics.展开更多
Although it is usually latent on citrus, apple, and pear, apple stem grooving virus(ASGV) poses a great risk to many sensitive cultivars. Since severe leaf yellow mottle mosaic(LYMM) symptoms have been observed on Hua...Although it is usually latent on citrus, apple, and pear, apple stem grooving virus(ASGV) poses a great risk to many sensitive cultivars. Since severe leaf yellow mottle mosaic(LYMM) symptoms have been observed on Huangjinmiyou(HJY) pummelos(Citrus grandis cv. Huangjinmiyou), a commercial variety that is widely cultivated in South China, high throughput sequencing(HTS) was used to find potential pathogens and only three divergent ASGV variants were identified. The three ASGV variants shared 81.03–82.34% genome-wide pairwise identities with each other, and were separately closest to other ASGV variants from different hosts and/or geographical regions, as indicated by viral phylogenies. However, these new variants may have developed from viral interstrain interactions, based on the results of recombination analysis. A large-scale survey using reverse transcription-PCR(RT-PCR) protocols designed for the three ASGV variants revealed a high incidence(92.7–100%) of ASGV in symptomatic HJY trees from 11 major citrusproducing regions in China. None of ASGV were detected in asymptomatic trees. Temperature treatments applied to the symptomatic HJY plants showed that ASGV is sensitive to high temperatures(30–35°C), at which not only the plants recovered, but also the viruses were not detected by RT-PCR, while at low temperatures(20–24°C), both the symptoms and viruses remained detectable. These data show that ASGV is associated with the LYMM disease prevalent on HJY in China, and this is the significant basis especially of taking appropriate measures timely to manage the disease.展开更多
目的:研究降钙素原(PCT)与超敏C反应蛋白(hs-CRP)指标在早期诊断新生儿败血症时的价值。方法:选取柘城县人民医院2017年5月至2019年11月收治的60例已确诊患有败血症的新生儿作为观察组,另选取同期60例健康新生儿作为对照组,比较两组间...目的:研究降钙素原(PCT)与超敏C反应蛋白(hs-CRP)指标在早期诊断新生儿败血症时的价值。方法:选取柘城县人民医院2017年5月至2019年11月收治的60例已确诊患有败血症的新生儿作为观察组,另选取同期60例健康新生儿作为对照组,比较两组间及观察组治疗前后PCT与hs-CRP的变化。结果:观察组PCT、hs-CRP、白细胞(WBC)、红细胞沉降率(ESR)呈阳性的患儿均多于对照组,差异具有统计学意义(P<0.05);观察组PCT、hs-CRP、WBC、ESR水平均高于对照组,差异具有统计学意义(P<0.05);与治疗后1 d相比,观察组患儿治疗后2 d、4 d、6 d PCT水平明显降低,治疗后4 d、6 d hs-CRP水平明显降低,差异具有统计学意义(P<0.05)。结论:对于患有败血症的新生儿而言,在诊断中尽早确定PCT与hs-CRP指标可作为一项重要的参考指标。展开更多
文摘时间差分算法(Temporal difference methods,TD)是一类模型无关的强化学习算法.该算法拥有较低的方差和可以在线(On-line)学习的优点,得到了广泛的应用.但对于一种给定的TD算法,往往只能通过调整步长参数或其他超参数来加速收敛,这也就造成了加速TD算法收敛的方法匮乏.针对此问题提出了一种利用蒙特卡洛算法(Monte Carlo methods,MC)来加速TD算法收敛的方法(Accelerate TD by MC,ATDMC).该方法不仅可以适用于绝大部分的TD算法,而且不需要改变在线学习的方式.为了证明方法的有效性,分别在同策略(On-policy)评估、异策略(Off-policy)评估和控制(Control)三个方面进行了实验.实验结果表明ATDMC方法可以有效地加速各类TD算法.
基金support of the National Natural Science Foundation of China (31071678)the Major Scientific and Technological Special of Zhejiang Province, China (2010C12026)+1 种基金the Ningbo Science and Technology Project, China (201002C1011001)Xiangshan Science and Technology Project, China(2010C0001)
文摘Identification and counting of rice light-trap pests are important to monitor rice pest population dynamics and make pest forecast. Identification and counting of rice light-trap pests manually is time-consuming, and leads to fatigue and an increase in the error rate. A rice light-trap insect imaging system is developed to automate rice pest identification. This system can capture the top and bottom images of each insect by two cameras to obtain more image features. A method is proposed for removing the background by color difference of two images with pests and non-pests. 156 features including color, shape and texture features of each pest are extracted into an support vector machine （SVM） classifier with radial basis kernel function. The seven-fold cross-validation is used to improve the accurate rate of pest identification. Four species of Lepidoptera rice pests are tested and achieved 97.5% average accurate rate.
基金financially supported by the National Natural Science Foundation of China(31271999)the Special Fund for Agro-scientific Research in the Public Interest,China(200903039-5)
文摘The sclerotia of Villosiclava virens were found commonly in high altitude and the temperate regions, where the temperatures are relatively low in rice filling stage. To make sure if low temperature induce the sclerotial formation in V. virens, the inoculated rice panicles in laboratory and the diseased rice panicles cut from paddy fields were treated under different temperatures. The results showed that 3 days of night temperature at 15°C were enough to induce the sclerotial formation. The low temperature was much more effective for young balls with intact membranes. After appearance of chlamydospores on the ball surfaces, the sclerotium could not differentiate anymore. The sclerotia began to differentiate below the chlamydospore layer and gradually grew onto the ball surfaces. This suggests that low temperature in the early development stage of false smut balls is an important factor to induce the sclerotial differentiation, and rice cultivars with long growth periods are able to produce more sclerotium-bearing balls, which will produce mass of spores in paddy field in the coming year.
基金funded by the Chongqing Natural Science Foundation Project, China (cstc2011jj A80025)
文摘The complete nucleotide sequence of an isolate of Citrus vein enation virus（CVEV-XZG） from China has been determined for the first time. The genome consisted of 5 983 nucleotides, coding for five open reading frames（ORFs）, had a similar genomic organization features with Pea enation mosaic virus（PEMV）. Nucleotide and deduced amino acid sequence identity of the five ORFs compared to isolate CVEV VE-1 range from 97.1 to 99.0% and 97.4 to 100.0%, these values compared to isolate PEMV-1 range from 45.2 to 51.6% and 31.1 to 45.2%. Phylogenetic analysis based on the complete genome sequence showed that the isolate CVEV-XZG had close relationship with Pea enation mosaic virus. The results supports CVEV may be a new member of genus Enamovirus. The full sequence of CVEV-XZG presented here may serve as a basis for future study of CVEV in China.
基金supported by the National Natural Science Foundation of China (31271999)the Special Fund for Agro-Scientific Research in the Public Interest, China (200903039-5)
文摘Rice false smut is caused by ascomycete Villosiclava virens, whose potential alternative hosts have been assumed previ- ously. Here its potential alternative hosts were surveyed and identified from 2008 to 2013 in the main rice-growing regions in China. Two common weeds in paddy fields, Digitaria sanguinalis Scop. and Echinochloa crusgalli （L.） Beauv., were found to present the similar symptoms to smut diseases in a few individuals in 2012 and 2013 in Zhejiang and Sichuan provinces of China, respectively. After the examinations of the spore morphology, their infection and extension mode in hosts, pathogen cell wall components, and molecular identification, the two pathogens were identified to be the Basidiomycetes, Ustilago syntherismae and Ustilago trichophora, respectively. So far there has been no alternative host of V. virens to be identified in China. These suggest that the alternative hosts of V. virens, if they do exist, are not possible to play an important role in the pathogen life cycle and the disease epidemics.
基金supported by the National Key R&D Program of China(2019YFD1001800)the National Natural Science Foundation of China(32072389)+1 种基金the Innovation Program for Chongqing’s Overseas Returnees(cx2019013)111 Project(B18044)from Ministry of Education(China)。
文摘Although it is usually latent on citrus, apple, and pear, apple stem grooving virus(ASGV) poses a great risk to many sensitive cultivars. Since severe leaf yellow mottle mosaic(LYMM) symptoms have been observed on Huangjinmiyou(HJY) pummelos(Citrus grandis cv. Huangjinmiyou), a commercial variety that is widely cultivated in South China, high throughput sequencing(HTS) was used to find potential pathogens and only three divergent ASGV variants were identified. The three ASGV variants shared 81.03–82.34% genome-wide pairwise identities with each other, and were separately closest to other ASGV variants from different hosts and/or geographical regions, as indicated by viral phylogenies. However, these new variants may have developed from viral interstrain interactions, based on the results of recombination analysis. A large-scale survey using reverse transcription-PCR(RT-PCR) protocols designed for the three ASGV variants revealed a high incidence(92.7–100%) of ASGV in symptomatic HJY trees from 11 major citrusproducing regions in China. None of ASGV were detected in asymptomatic trees. Temperature treatments applied to the symptomatic HJY plants showed that ASGV is sensitive to high temperatures(30–35°C), at which not only the plants recovered, but also the viruses were not detected by RT-PCR, while at low temperatures(20–24°C), both the symptoms and viruses remained detectable. These data show that ASGV is associated with the LYMM disease prevalent on HJY in China, and this is the significant basis especially of taking appropriate measures timely to manage the disease.
文摘目的:研究降钙素原(PCT)与超敏C反应蛋白(hs-CRP)指标在早期诊断新生儿败血症时的价值。方法:选取柘城县人民医院2017年5月至2019年11月收治的60例已确诊患有败血症的新生儿作为观察组,另选取同期60例健康新生儿作为对照组,比较两组间及观察组治疗前后PCT与hs-CRP的变化。结果:观察组PCT、hs-CRP、白细胞(WBC)、红细胞沉降率(ESR)呈阳性的患儿均多于对照组,差异具有统计学意义(P<0.05);观察组PCT、hs-CRP、WBC、ESR水平均高于对照组,差异具有统计学意义(P<0.05);与治疗后1 d相比,观察组患儿治疗后2 d、4 d、6 d PCT水平明显降低,治疗后4 d、6 d hs-CRP水平明显降低,差异具有统计学意义(P<0.05)。结论:对于患有败血症的新生儿而言,在诊断中尽早确定PCT与hs-CRP指标可作为一项重要的参考指标。
