Dielectric data for volcanic scoria and basalt on the earth at microwave frequency are extremely sparse, and also crucial for volcanic terrains imaging, and development. In consideration of their similarity to lunar r...Dielectric data for volcanic scoria and basalt on the earth at microwave frequency are extremely sparse, and also crucial for volcanic terrains imaging, and development. In consideration of their similarity to lunar regolith (soils and rocks) in chemical and mineral composition, the dielectric data is significative for passive and active microwave remote sensing on the Moon. This study provides the data about the dielectric properties of three kinds of scoria and two kinds of basalt in China. The method put forward in this paper is also applicable for measuring the dielectric properties of dry rocks and other granular ground materials with low complex dielectric constants. Firstly, the authors measured the e' and tanδ values of strip specimens prepared from the mixture of scoria or basalt powder and polythene with the resonant cavity perturbation method at 9370 MHz. Secondly, from the ε' and tanδ values of the mixture, the ε' s and tanδ s values of solid scoria and basalt were calculated using Lichtenecker's mixture formulae. Finally, the effective complex dielectric constants, ε' e and tanδ e , of scoria at different bulk densities were calculated. The results have shown that the ε' s and tanδ s values of all solid basaltic materials measured (both solid basaltic scoria or basalt) are approximately 7 and 0.05, respectively. With increasing bulk density of scoria, the ε' c and tanδ e values of scoria increase significantly.展开更多
Biological control is usually the first choice of control and prevention method for integrated pest management （IPM） strategies and has now been widely implemented by Indonesian oil palm plantations. Entomopathogeni...Biological control is usually the first choice of control and prevention method for integrated pest management （IPM） strategies and has now been widely implemented by Indonesian oil palm plantations. Entomopathogenic fungus, i.e., Metarhizium anisopliae, Cordyceps militaris and Beauveria bassiana have been demonstrated to control renowned pests of oil palm. Metarhizium has been used to control Oryctes larvae and the mortality has ranged from 91.67% to 100% in laboratory and 7.4% to 88.75% in the field. Metarhizium has been applied in combination with a termite baiting system （TBS） to control termites in the field for preventive and curative action as well. In many oil palm plantations in Indonesia, Cordyceps has been used to reduce the field moth population ofSetothosea asigna. Application of Cordyceps within the oil palm circle was able to infect S. asigna pupae up to 80%. Meanwhile, Beauveria in an effervescent formulation was demonstrated to have better efficacy on Darna trima larvae. A significant finding on the biological control of basal stem rot disease （Ganoderma） was the isolation of Trichoderma sp. and Gliocladium sp.. The efficacy was conducted with promising result and techniques on the application of Triehoderma have been developed, i.e., hole-in-hole system, surgery and a mounding method. However, as the roots developed, Trichoderma was no longer able to protect the palm from Ganoderma. In spite of that, the use of Trichoderma still prolonged the life ofoil palms by up to 2-3 years. Another fungi belonging to vesicular arbuscular mychorrhiza （VAM） has been developed to control Ganoderma. The efficacy in the nursery showed promising results and the Ganoderma incidence remained low compared to the untreated control. Large scale field trials are ongoing. Challenges on the implementation of biological control in oil palm plantations are because of application and availability of biopesticides/natural enemies. Therefore, advances in research on the formulation of biological control agents are still needed.展开更多
Two-parameter gamma distributions are widely used in liability theory, lifetime data analysis, financial statistics, and other areas. Finite mixtures of gamma distributions are their natural extensions, and they are p...Two-parameter gamma distributions are widely used in liability theory, lifetime data analysis, financial statistics, and other areas. Finite mixtures of gamma distributions are their natural extensions, and they are particularly useful when the population is suspected of heterogeneity. These distributions are successfully employed in various applications, but many researchers falsely believe that the maximum likelihood estimator of the mixing distribution is consistent. Similarly to finite mixtures of normal distributions, the likelihood function under finite gamma mixtures is unbounded. Because of this, each observed value leads to a global maximum that is irrelevant to the true distribution. We apply a seemingly negligible penalty to the likelihood according to the shape parameters in the fitted model. We show that this penalty restores the consistency of the likelihoodbased estimator of the mixing distribution under finite gamma mixture models. We present simulation results to validate the consistency conclusion, and we give an example to illustrate the key points.展开更多
基金the National Natural Science Foundation of China(Grant No.40473036and 40373037) the project of knowledge-innovation program of the Chinese Academy of Sciences(Grant No.KZCX2-115).
文摘Dielectric data for volcanic scoria and basalt on the earth at microwave frequency are extremely sparse, and also crucial for volcanic terrains imaging, and development. In consideration of their similarity to lunar regolith (soils and rocks) in chemical and mineral composition, the dielectric data is significative for passive and active microwave remote sensing on the Moon. This study provides the data about the dielectric properties of three kinds of scoria and two kinds of basalt in China. The method put forward in this paper is also applicable for measuring the dielectric properties of dry rocks and other granular ground materials with low complex dielectric constants. Firstly, the authors measured the e' and tanδ values of strip specimens prepared from the mixture of scoria or basalt powder and polythene with the resonant cavity perturbation method at 9370 MHz. Secondly, from the ε' and tanδ values of the mixture, the ε' s and tanδ s values of solid scoria and basalt were calculated using Lichtenecker's mixture formulae. Finally, the effective complex dielectric constants, ε' e and tanδ e , of scoria at different bulk densities were calculated. The results have shown that the ε' s and tanδ s values of all solid basaltic materials measured (both solid basaltic scoria or basalt) are approximately 7 and 0.05, respectively. With increasing bulk density of scoria, the ε' c and tanδ e values of scoria increase significantly.
文摘Biological control is usually the first choice of control and prevention method for integrated pest management （IPM） strategies and has now been widely implemented by Indonesian oil palm plantations. Entomopathogenic fungus, i.e., Metarhizium anisopliae, Cordyceps militaris and Beauveria bassiana have been demonstrated to control renowned pests of oil palm. Metarhizium has been used to control Oryctes larvae and the mortality has ranged from 91.67% to 100% in laboratory and 7.4% to 88.75% in the field. Metarhizium has been applied in combination with a termite baiting system （TBS） to control termites in the field for preventive and curative action as well. In many oil palm plantations in Indonesia, Cordyceps has been used to reduce the field moth population ofSetothosea asigna. Application of Cordyceps within the oil palm circle was able to infect S. asigna pupae up to 80%. Meanwhile, Beauveria in an effervescent formulation was demonstrated to have better efficacy on Darna trima larvae. A significant finding on the biological control of basal stem rot disease （Ganoderma） was the isolation of Trichoderma sp. and Gliocladium sp.. The efficacy was conducted with promising result and techniques on the application of Triehoderma have been developed, i.e., hole-in-hole system, surgery and a mounding method. However, as the roots developed, Trichoderma was no longer able to protect the palm from Ganoderma. In spite of that, the use of Trichoderma still prolonged the life ofoil palms by up to 2-3 years. Another fungi belonging to vesicular arbuscular mychorrhiza （VAM） has been developed to control Ganoderma. The efficacy in the nursery showed promising results and the Ganoderma incidence remained low compared to the untreated control. Large scale field trials are ongoing. Challenges on the implementation of biological control in oil palm plantations are because of application and availability of biopesticides/natural enemies. Therefore, advances in research on the formulation of biological control agents are still needed.
基金supported by Grants from One Thousand Talents at Yunnan Universitya Discovery Grant from the Natural Sciences and Engineering Research Council of Canada (Grant No. RGPIN–2014–03743)
文摘Two-parameter gamma distributions are widely used in liability theory, lifetime data analysis, financial statistics, and other areas. Finite mixtures of gamma distributions are their natural extensions, and they are particularly useful when the population is suspected of heterogeneity. These distributions are successfully employed in various applications, but many researchers falsely believe that the maximum likelihood estimator of the mixing distribution is consistent. Similarly to finite mixtures of normal distributions, the likelihood function under finite gamma mixtures is unbounded. Because of this, each observed value leads to a global maximum that is irrelevant to the true distribution. We apply a seemingly negligible penalty to the likelihood according to the shape parameters in the fitted model. We show that this penalty restores the consistency of the likelihoodbased estimator of the mixing distribution under finite gamma mixture models. We present simulation results to validate the consistency conclusion, and we give an example to illustrate the key points.
