A combined study of CL imaging, LA-ICP-MS U-Pb dating and trace element analysis were carried out for zircon grains from high-pressure basic granulite at Song- shugou in North Qinling. The zircons display core-rim in-...A combined study of CL imaging, LA-ICP-MS U-Pb dating and trace element analysis were carried out for zircon grains from high-pressure basic granulite at Song- shugou in North Qinling. The zircons display core-rim in- ternal texture. The cores are made up of sector or planar domains, partially displaying weak zoning or misty texture, and have the feature of low content of Th, U, REE, HREE, low Th/U ratio and high (Nd/Yb)N ratio, and the REE pat- tern typical for zircon coexisting with garnet. These features indicate the metamorphic genesis for the zircon cores. The rims have narrow light margins (<30 μm in width) around the cores and boundaries between core and rim are rounded or lough-like, indicating that the rims were formed during retrograde metamorphism. U-Pb isotopic data of 24 spots from the cores of 11 zircon grains yield a 206 Pb/238U weighted average age of 485±3.3 Ma, which is interpreted as the peak metamorphic age of high-pressure (HP) basic granulite. This age is well consistent within error with that of ultra- high-pressure (UHP) eclogite and its country rock gneiss (507±37 Ma) that occur at the north side of the Qinling Group, possibly indicating the occurrence of two contempo- raneous Early-Paleozoic HP to UHP metamorphic rock belts on the north and south sides of the Qinling Group. Combin- ing with the regional geological studies and the distribution of Early-Paleozoic granites related to subduction and colli- sion, the two HP to UHP metamorphic belts may be the products of continental crust bi-directional deep subduction toward Qinling micro-block caused by the subduction and collision of Paleozoic Qinling ocean and Erlangping ocean, respectively.展开更多
Cathodoluminescence (CL) and mineral inclu- sions investigations show that zircons from Yinggelisayi UHP metamorphosed granitoid gneiss in Altyn Tagh exhibit core-mantle-rim internal texture with magmatic residual cor...Cathodoluminescence (CL) and mineral inclu- sions investigations show that zircons from Yinggelisayi UHP metamorphosed granitoid gneiss in Altyn Tagh exhibit core-mantle-rim internal texture with magmatic residual core, the metamorphic overgrowth mantle and the late stage rim. SHRIMP 206 Pb/238U ages of 5 spots from the mantles vary from 484±11 to 491±12 Ma with Th/U ratios from 0.01 to 0.03, yielding a weighted average age of 487±10 Ma (2σ ) as the age of the UHP metamorphosed granitoid gneiss. The 206Pb/238U ages from the oscillatory zoned cores range from 809±19 to 885±21 Ma with Th/U ratios ranging from 0.42 to 0.83, which are interpreted as the crystallization age of the protolith of the granitoid gneiss. The metamorphic age (487±10 Ma) of the UHP metamorphosed granitoid gneiss, well consistent with the peak metamorphic age (about 500 Ma) of the UHP eclogite with crystallization age of the proto- lith between 809±19 and 885±21 Ma at Jianggelisayi in west- ern Altyn Tagh, indicates the existence of a UHPM belt along the south margin of the Altyn Tagh as a result of deep sub- duction during Early Paleozoic age of previously existing continental crust.展开更多
The Shicaogou granite has been identified as a magnesian (Fe-number=0.71-0.76), calcic to calc-alkalic (MALI=3.84-5.76) and peraluminous (ASI=1.06-1.13) granite of the syn-collisional S-type, with high SiO2(>71%), ...The Shicaogou granite has been identified as a magnesian (Fe-number=0.71-0.76), calcic to calc-alkalic (MALI=3.84-5.76) and peraluminous (ASI=1.06-1.13) granite of the syn-collisional S-type, with high SiO2(>71%), A12O3 (>13%) and Na2O+K2O (6.28%-7.33%, equal for NaO2 and K2O). Trace element and REE analyses show that the granite is rich in LILE such as of Rb, Sr, Ba and Th, and poor in HFSE like Yb, Y, Zr and Hf. Its Rb/Sr ratio is greater than 1; the contents of Nb and Ta, and the ratio of Nb/Ta as well as the REE geochemical features (e.g. REE abundance, visible fractionation of LREE and HREE and medium to pronounced negative Eu anomalies) are all similar to those of crust-origin, continent-continent syn-collisional granite. Moreover, the granite exhibits almost the same pattern as that of the typical continent-continent syn-collisional granite on the spider diagram and all samples fall within the syn-collisional granite field.The cathodoluminescence (CL) investigations have revealed that the zircon from the Shicaogou granite represents a typical magmatic product characterized by its colorless, transparent and euhedral crystals, and distinct zoning of oscillatory bands. Residual cores of irregular zircon can be found in a few enhedral grains. Trace element studies of the zircon grains, with high contents of P, Y, Hf, Th, U and REE and high ratios of Th/U, obviously positive Ce anomalies and HREE enrichment compared to LREE, also result in the same conclusion.The LA-ICP-MS U-Pb isotopic data from 24 spots of 21 zircon grains demonstrate that 20 spots in the oscillatory zone yield an average weighted 206Pb/238U age of 925±11 Ma, indicating that the Shicaogou granite was formed in the Neoproterozoic. Combined with other Neoproterozoic syn-collisional granites found in the study area, the present geochronological determination can further reveal that collision-amalgamation events could have occurred among some continental blocks in the Qinling orogenic belt during the Neoproterozoic. This in turn provides an accu展开更多
While the demand for deep ultraviolet(DUV)light sources is rapidly growing,the efficiency of current AlGaN-based DUV light-emitting diodes(LEDs)remains very low due to their fundamentally limited light-extraction effi...While the demand for deep ultraviolet(DUV)light sources is rapidly growing,the efficiency of current AlGaN-based DUV light-emitting diodes(LEDs)remains very low due to their fundamentally limited light-extraction efficiency(LEE),calling for a novel LEE-enhancing approach to deliver a real breakthrough.Here,we propose sidewall emission-enhanced(SEE)DUV LEDs having multiple light-emitting mesa stripes to utilize inherently strong transverse-magnetic polarized light from the AlGaN active region and three-dimensional reflectors between the stripes.The SEE DUV LEDs show much enhanced light output power with a strongly upward-directed emission due to the exposed sidewall of the active region and Al-coated selective-area-grown n-type GaN micro-reflectors.The devices also show reduced operating voltage due to better n-type ohmic contact formed on the regrown n-GaN stripes when compared with conventional LEDs.Accordingly,the proposed approach simultaneously improves optical and electrical properties.In addition,strategies to further enhance the LEE up to the theoretical optimum value and control emission directionality are discussed.展开更多
In this paper, oscillation properties of the solutions of impulsive hyperbolic equation with delay are investigated via the method of differential inequalities. Sufficient conditions for oscillations of the solutions ...In this paper, oscillation properties of the solutions of impulsive hyperbolic equation with delay are investigated via the method of differential inequalities. Sufficient conditions for oscillations of the solutions are established.展开更多
Authorization management is important precondition and foundation for coordinating and resource sharing in open networks. Recently, authorization based on trust is widely used whereby access rights to shared resource ...Authorization management is important precondition and foundation for coordinating and resource sharing in open networks. Recently, authorization based on trust is widely used whereby access rights to shared resource are granted on the basis of their trust relation in distributed environment. Nevertheless, dynamic change of the status of credential and chain of trust induces to uncertainty of trust relation. Considering uncertainty of authorization and analyzing deficiency of authorization model only based on trust, we proposes joint trust-risk evaluation and build the model based on fuzzy set theory, and make use of the membership grade of fuzzy set to express joint trust-risk relation. Finally, derivation principle and constraint principle of joint trust-risk relationships are presented. The authorization management model is defined based on joint trust-risk evaluation, proof of compliance and separation of duty are analyzed. The proposed model depicts not only trust relationship between principals, but also security problem of authorization.展开更多
The effects of different chemical fertilizer combinations (N, P and K) oncrop yield, N uptake and nitrate distribution and accumulation to a depth of 100 cm were studied ina cinnamon fluvo-aquic soil profile (Beijing)...The effects of different chemical fertilizer combinations (N, P and K) oncrop yield, N uptake and nitrate distribution and accumulation to a depth of 100 cm were studied ina cinnamon fluvo-aquic soil profile (Beijing) with a continuous winter wheat-summer maize croppingsystem for nine years. The experiment consisted of 7 treatments: no fertilizer control (CK); Nalone, N in combination with K (NK), P (NP), and P and K (NPK and N1PK); and P and K in combinationwithout N (PK). The rate of N was 150 kg ha^(-1) for the N treatments except Treatment N1PK withhigher N rate (195 kg ha^(-1)), and the rates of P (P_2O_5) and K (K2O) were 75 and 37.5 kg ha^(-1),respectively. The applications of N combined with P and K (NK, NP and NPK) resulted in higher cropyields than a single application of N. The yields followed the order: NPK > NP > N1PK > PK > NK > N> CK for winter wheat, and NPK > N1PK > NP > NK > N > PK > CK for summer maize. Supplement of N withP or K, or both P and K resulted in a higher average N uptake of the two crops, which was in adecreasing order NPK > NP > N1PK > NK > N > PK > CK. The combinations also increased apparent Nrecovery more than N alone and CK. The nitrate content in the profile was thus reduced more in thecombination treatments. The nitrate accumulation in the soil profiles followed the order: N > NK >N1PK > NPK > NP > CK > PK. Higher N uptake by the adequately fertilized crops (Treatment NPK)reduced nitrate accumulation in the profile and thus reduced nitrate leaching. The optimum N:P:Kratio was thus of paramount importance in increasing yields and N uptake of crops and reducingnitrate leaching losses.展开更多
In order toclarify regional ecological security status and formation mechanism of regional ecological security barriers in underdeveloped regions of China,we took Yunnan province as a case to evaluate its regional eco...In order toclarify regional ecological security status and formation mechanism of regional ecological security barriers in underdeveloped regions of China,we took Yunnan province as a case to evaluate its regional ecological security by using entropy matter-element model,comprehensive index and GIS spatial method,and we diagnosed itsobstacle factors through obstacle degree model. We found a low overall level of regional ecological security in Yunnan. Only Kunmingfell into the good level, 68% of the regions were below the critical safe level. For the vast majority of regions in Yunnan, their regional ecological security was unstable. The indexes related to per capita resources, geological and topographyenvironment, economic, and technologywere at the unsafe or dangerous level.The indexes related to urban expansion, level of income, cultivated land quality were at the level of critical safety. The indexes concerning urban management capacity, airqualityand waterenvironment were at the good or ideallevel. Yunnan's regional ecological security was not good due to natural obstructive environment itself, simultaneously lower backward economic and social level restricted the ability of ecological security response to manage ragile ecological environment. The results of the composite index wereroughly consistent with those of the entropy weight matterelement model. The mean values of the classification index,from high to low, were: the state index>the response index>the pressure index. The state index and the response index had a significant mutual promotion to each other.The regions with good composite index, state index and response index mainly distributed in the central regions of Yunnan Province. Spatial autocorrelation of regional ecological security level in Yunnan was not obvious. Water resources, economic and social development were main obstacle factors of the regional ecological security.When distinguishing with obstacle type, Kunming belonged to natural ecological environment barrier type, while other regions展开更多
A stable transformation system for the expression of foreign genes in the unicellular greenmarine alga (Dunaliella salina Teod.) was established. Using electroporation, the alga was transformed witha plasmid containin...A stable transformation system for the expression of foreign genes in the unicellular greenmarine alga (Dunaliella salina Teod.) was established. Using electroporation, the alga was transformed witha plasmid containing the hepatitis B surface antigen (HBsAg) gene and the chloramphenicol acetyltransferase(CAT) gene as a selectable gene. PCR and Southern blotting analysis indicated that the HBsAEgene wasintegrated into the D. salina genome. Northern dotting analysis showed that the HBsAg gene was expressedat the mRNA level. The stable expression of HBsAg protein in transformants was confirmed by HBsAgenzyme-linked immunosorbent assay (HBsAg EUSA) and Western blotting analysis. Also, PCR and Southernblotting analyses showed that the CA Tgene was integrated into the D, salina genome, and CAT EUSAindicated that CAT protein was stably expressed in the cells. The introduced HBsAg DNA and HBsAgprotein expression were stably maintained for at least 60 generations in media devoid of chloramphenicol.This is the first report of the stable expression of foreign genes in D. salina.展开更多
Background Awareness under general anesthesia is a serious complication which leads to psychiatric disorders. The incidence of awareness in patients undergoing cardiac surgery has been reported in as many as 1.5%-23% ...Background Awareness under general anesthesia is a serious complication which leads to psychiatric disorders. The incidence of awareness in patients undergoing cardiac surgery has been reported in as many as 1.5%-23% in foreign countries. But so far, medical literature about awareness during cardiac surgery is still rare in China. Therefore, we investigated the incidence of awareness in patients undergoing different kinds of cardiac surgery, the phases when awareness occured and the effect of cardiopulmonary bypass on the incidence of awareness in coronary artery bypass grafting in Beijing.Methods Patients' recall of awareness during cardiac surgery was assessed. One hundred patients undergoing coronary artery bypass grafting (CABG) in Chaoyang Hospital, Beijing, one hundred patients undergoing CABG and one hundred patients undergoing valve replacement or septal defect repair in Fuwai Hospital, Beijing, were interviewed 3-6 days after surgery. Every report obout patients on recall of awareness was recorded. An independent research team, blinded to patients' surgery and anesthesia, assessed every report of awareness.Results The incidence of awareness of patients received CABG under cardiopulmonary bypass (CPB), off -pump CABG, septal repair or valve replacement under CPB was 4.7% (5 of 106 cases), 9.6% (9 of 94 cases) and 4% (4 of 100 cases), respectively. CPB did not greatly affect the incidence of awareness during the period of CABG (P>0.05). The incidence of awareness of patients who received CABG under CPB did not increase significantly, in comparison with that of patients who received septal repair or valve replacement under CPB in Fuwai Hospital (P>0.05). Awareness easily occurred before bypass grafting or CPB.Conclusions Awareness mainly occurs before bypass grafting or CPB in cardiac surgery. Most cases with awareness have auditory perceptions. CPB is not a main factor which affects the incidence of awareness of CABG. Surgical types do not affect the incidence of awareness of patients under CPB.展开更多
针对单声矢量传感器(Acoustic vector sensor,AVS)脉冲噪声环境下的多声源波达方向(Direction of arrival,DOA)跟踪问题,利用α稳定分布能更好地建模脉冲噪声的性质,提出α稳定分布下的多伯努利DOA跟踪算法。由于α稳定分布不具有有限...针对单声矢量传感器(Acoustic vector sensor,AVS)脉冲噪声环境下的多声源波达方向(Direction of arrival,DOA)跟踪问题,利用α稳定分布能更好地建模脉冲噪声的性质,提出α稳定分布下的多伯努利DOA跟踪算法。由于α稳定分布不具有有限协方差,该算法采用分数低阶距(Fractional Lower Order Moment,FLOM)代替协方差矩阵,对FLOM进行特征分解构造噪声子空间,生成FLOM-MUSIC空间谱函数作为多伯努利滤波器的伪似然函数,并对其指数加权,改善了传统似然函数的发散和平坦问题,使得粒子的重采样更有效。该算法的优点是不需要预先知道声源个数,利用先验信息和当前量测信息可以直接对当前声源进行跟踪。仿真结果表明,该算法能有效跟踪脉冲噪声环境下单一AVS声源的数目和状态。展开更多
针对目标检测概率较低导致单个传感器无法对目标进行有效检测并跟踪的问题,本文提出了多传感器箱粒子概率假设密度(multi-sensor box particle probability hypothesis density filter,MS-BOX-PHD)滤波器。MS-BOX-PHD滤波器首先将多个...针对目标检测概率较低导致单个传感器无法对目标进行有效检测并跟踪的问题,本文提出了多传感器箱粒子概率假设密度(multi-sensor box particle probability hypothesis density filter,MS-BOX-PHD)滤波器。MS-BOX-PHD滤波器首先将多个传感器的量测转换、融合成为一个量测集合,并利用箱粒子概率假设密度(box particle probability hypothesis density filter,BOX-PHD)滤波器对多个目标的状态进行预测和更新。数值实验表明,相较于单传感器箱粒子概率假设密度(Single-BOX-PHD)滤波器,MS-BOX-PHD滤波器在目标检测概率较低时,能够有效地对多目标的状态和数目进行估计;相较于区间量测下多传感器标准PHD粒子(multi-sensor standard probability hypothesis density particle filter with interval measurement,IM-PHD-PF)滤波器,在达到相同的跟踪性能时,计算效率提升了38.57%。展开更多
文摘A combined study of CL imaging, LA-ICP-MS U-Pb dating and trace element analysis were carried out for zircon grains from high-pressure basic granulite at Song- shugou in North Qinling. The zircons display core-rim in- ternal texture. The cores are made up of sector or planar domains, partially displaying weak zoning or misty texture, and have the feature of low content of Th, U, REE, HREE, low Th/U ratio and high (Nd/Yb)N ratio, and the REE pat- tern typical for zircon coexisting with garnet. These features indicate the metamorphic genesis for the zircon cores. The rims have narrow light margins (<30 μm in width) around the cores and boundaries between core and rim are rounded or lough-like, indicating that the rims were formed during retrograde metamorphism. U-Pb isotopic data of 24 spots from the cores of 11 zircon grains yield a 206 Pb/238U weighted average age of 485±3.3 Ma, which is interpreted as the peak metamorphic age of high-pressure (HP) basic granulite. This age is well consistent within error with that of ultra- high-pressure (UHP) eclogite and its country rock gneiss (507±37 Ma) that occur at the north side of the Qinling Group, possibly indicating the occurrence of two contempo- raneous Early-Paleozoic HP to UHP metamorphic rock belts on the north and south sides of the Qinling Group. Combin- ing with the regional geological studies and the distribution of Early-Paleozoic granites related to subduction and colli- sion, the two HP to UHP metamorphic belts may be the products of continental crust bi-directional deep subduction toward Qinling micro-block caused by the subduction and collision of Paleozoic Qinling ocean and Erlangping ocean, respectively.
文摘Cathodoluminescence (CL) and mineral inclu- sions investigations show that zircons from Yinggelisayi UHP metamorphosed granitoid gneiss in Altyn Tagh exhibit core-mantle-rim internal texture with magmatic residual core, the metamorphic overgrowth mantle and the late stage rim. SHRIMP 206 Pb/238U ages of 5 spots from the mantles vary from 484±11 to 491±12 Ma with Th/U ratios from 0.01 to 0.03, yielding a weighted average age of 487±10 Ma (2σ ) as the age of the UHP metamorphosed granitoid gneiss. The 206Pb/238U ages from the oscillatory zoned cores range from 809±19 to 885±21 Ma with Th/U ratios ranging from 0.42 to 0.83, which are interpreted as the crystallization age of the protolith of the granitoid gneiss. The metamorphic age (487±10 Ma) of the UHP metamorphosed granitoid gneiss, well consistent with the peak metamorphic age (about 500 Ma) of the UHP eclogite with crystallization age of the proto- lith between 809±19 and 885±21 Ma at Jianggelisayi in west- ern Altyn Tagh, indicates the existence of a UHPM belt along the south margin of the Altyn Tagh as a result of deep sub- duction during Early Paleozoic age of previously existing continental crust.
基金the National NaturalScience Foundation of China(Grant No.140032010-C,49972063)the National Key Basic Research andDevelopment Project of China(Grant No.G1999075508)+3 种基金the Ministry of Education's Teacher Fund(No.40133020)the Natural Science Foundation of Shaanxi Province(2002D03)the Special Foundation of the Department ofEducation of Shaanxi Province(01JK108) the ScienceFoundation of Northwest University.
文摘The Shicaogou granite has been identified as a magnesian (Fe-number=0.71-0.76), calcic to calc-alkalic (MALI=3.84-5.76) and peraluminous (ASI=1.06-1.13) granite of the syn-collisional S-type, with high SiO2(>71%), A12O3 (>13%) and Na2O+K2O (6.28%-7.33%, equal for NaO2 and K2O). Trace element and REE analyses show that the granite is rich in LILE such as of Rb, Sr, Ba and Th, and poor in HFSE like Yb, Y, Zr and Hf. Its Rb/Sr ratio is greater than 1; the contents of Nb and Ta, and the ratio of Nb/Ta as well as the REE geochemical features (e.g. REE abundance, visible fractionation of LREE and HREE and medium to pronounced negative Eu anomalies) are all similar to those of crust-origin, continent-continent syn-collisional granite. Moreover, the granite exhibits almost the same pattern as that of the typical continent-continent syn-collisional granite on the spider diagram and all samples fall within the syn-collisional granite field.The cathodoluminescence (CL) investigations have revealed that the zircon from the Shicaogou granite represents a typical magmatic product characterized by its colorless, transparent and euhedral crystals, and distinct zoning of oscillatory bands. Residual cores of irregular zircon can be found in a few enhedral grains. Trace element studies of the zircon grains, with high contents of P, Y, Hf, Th, U and REE and high ratios of Th/U, obviously positive Ce anomalies and HREE enrichment compared to LREE, also result in the same conclusion.The LA-ICP-MS U-Pb isotopic data from 24 spots of 21 zircon grains demonstrate that 20 spots in the oscillatory zone yield an average weighted 206Pb/238U age of 925±11 Ma, indicating that the Shicaogou granite was formed in the Neoproterozoic. Combined with other Neoproterozoic syn-collisional granites found in the study area, the present geochronological determination can further reveal that collision-amalgamation events could have occurred among some continental blocks in the Qinling orogenic belt during the Neoproterozoic. This in turn provides an accu
基金The authors gratefully acknowledge the support by the International Collaborative R&D Program of the Korea Institute for Advancement of Technology(KIAT)(M0000078,Development of Deep UV LED Technology for Industry and Medical Application)the Industrial Strategic Technology Development Program(10041878,Development of WPE 75%LED device process and standard evaluation technology)the IT R&D Program(10035598,180 lm W21 High-efficiency Nano-based LEDs)funded by the Ministry of Trade,Industry&Energy(MOTIE,Korea)。
文摘While the demand for deep ultraviolet(DUV)light sources is rapidly growing,the efficiency of current AlGaN-based DUV light-emitting diodes(LEDs)remains very low due to their fundamentally limited light-extraction efficiency(LEE),calling for a novel LEE-enhancing approach to deliver a real breakthrough.Here,we propose sidewall emission-enhanced(SEE)DUV LEDs having multiple light-emitting mesa stripes to utilize inherently strong transverse-magnetic polarized light from the AlGaN active region and three-dimensional reflectors between the stripes.The SEE DUV LEDs show much enhanced light output power with a strongly upward-directed emission due to the exposed sidewall of the active region and Al-coated selective-area-grown n-type GaN micro-reflectors.The devices also show reduced operating voltage due to better n-type ohmic contact formed on the regrown n-GaN stripes when compared with conventional LEDs.Accordingly,the proposed approach simultaneously improves optical and electrical properties.In addition,strategies to further enhance the LEE up to the theoretical optimum value and control emission directionality are discussed.
基金This research is supported by National Natural Science Foundation of China (No.10361003).
文摘In this paper, oscillation properties of the solutions of impulsive hyperbolic equation with delay are investigated via the method of differential inequalities. Sufficient conditions for oscillations of the solutions are established.
基金Supported by the National Natural Science Foundation of China (60403027)
文摘Authorization management is important precondition and foundation for coordinating and resource sharing in open networks. Recently, authorization based on trust is widely used whereby access rights to shared resource are granted on the basis of their trust relation in distributed environment. Nevertheless, dynamic change of the status of credential and chain of trust induces to uncertainty of trust relation. Considering uncertainty of authorization and analyzing deficiency of authorization model only based on trust, we proposes joint trust-risk evaluation and build the model based on fuzzy set theory, and make use of the membership grade of fuzzy set to express joint trust-risk relation. Finally, derivation principle and constraint principle of joint trust-risk relationships are presented. The authorization management model is defined based on joint trust-risk evaluation, proof of compliance and separation of duty are analyzed. The proposed model depicts not only trust relationship between principals, but also security problem of authorization.
基金Project supported by the Ministry of Agriculture, China (No. 95-17-03-01).
文摘The effects of different chemical fertilizer combinations (N, P and K) oncrop yield, N uptake and nitrate distribution and accumulation to a depth of 100 cm were studied ina cinnamon fluvo-aquic soil profile (Beijing) with a continuous winter wheat-summer maize croppingsystem for nine years. The experiment consisted of 7 treatments: no fertilizer control (CK); Nalone, N in combination with K (NK), P (NP), and P and K (NPK and N1PK); and P and K in combinationwithout N (PK). The rate of N was 150 kg ha^(-1) for the N treatments except Treatment N1PK withhigher N rate (195 kg ha^(-1)), and the rates of P (P_2O_5) and K (K2O) were 75 and 37.5 kg ha^(-1),respectively. The applications of N combined with P and K (NK, NP and NPK) resulted in higher cropyields than a single application of N. The yields followed the order: NPK > NP > N1PK > PK > NK > N> CK for winter wheat, and NPK > N1PK > NP > NK > N > PK > CK for summer maize. Supplement of N withP or K, or both P and K resulted in a higher average N uptake of the two crops, which was in adecreasing order NPK > NP > N1PK > NK > N > PK > CK. The combinations also increased apparent Nrecovery more than N alone and CK. The nitrate content in the profile was thus reduced more in thecombination treatments. The nitrate accumulation in the soil profiles followed the order: N > NK >N1PK > NPK > NP > CK > PK. Higher N uptake by the adequately fertilized crops (Treatment NPK)reduced nitrate accumulation in the profile and thus reduced nitrate leaching. The optimum N:P:Kratio was thus of paramount importance in increasing yields and N uptake of crops and reducingnitrate leaching losses.
基金funded by the National Science-technology Support Plan Projects of China (Grant No.2015BAD07B0105)Yunnan Education Department Fundof China (2014Y315)
文摘In order toclarify regional ecological security status and formation mechanism of regional ecological security barriers in underdeveloped regions of China,we took Yunnan province as a case to evaluate its regional ecological security by using entropy matter-element model,comprehensive index and GIS spatial method,and we diagnosed itsobstacle factors through obstacle degree model. We found a low overall level of regional ecological security in Yunnan. Only Kunmingfell into the good level, 68% of the regions were below the critical safe level. For the vast majority of regions in Yunnan, their regional ecological security was unstable. The indexes related to per capita resources, geological and topographyenvironment, economic, and technologywere at the unsafe or dangerous level.The indexes related to urban expansion, level of income, cultivated land quality were at the level of critical safety. The indexes concerning urban management capacity, airqualityand waterenvironment were at the good or ideallevel. Yunnan's regional ecological security was not good due to natural obstructive environment itself, simultaneously lower backward economic and social level restricted the ability of ecological security response to manage ragile ecological environment. The results of the composite index wereroughly consistent with those of the entropy weight matterelement model. The mean values of the classification index,from high to low, were: the state index>the response index>the pressure index. The state index and the response index had a significant mutual promotion to each other.The regions with good composite index, state index and response index mainly distributed in the central regions of Yunnan Province. Spatial autocorrelation of regional ecological security level in Yunnan was not obvious. Water resources, economic and social development were main obstacle factors of the regional ecological security.When distinguishing with obstacle type, Kunming belonged to natural ecological environment barrier type, while other regions
文摘A stable transformation system for the expression of foreign genes in the unicellular greenmarine alga (Dunaliella salina Teod.) was established. Using electroporation, the alga was transformed witha plasmid containing the hepatitis B surface antigen (HBsAg) gene and the chloramphenicol acetyltransferase(CAT) gene as a selectable gene. PCR and Southern blotting analysis indicated that the HBsAEgene wasintegrated into the D. salina genome. Northern dotting analysis showed that the HBsAg gene was expressedat the mRNA level. The stable expression of HBsAg protein in transformants was confirmed by HBsAgenzyme-linked immunosorbent assay (HBsAg EUSA) and Western blotting analysis. Also, PCR and Southernblotting analyses showed that the CA Tgene was integrated into the D, salina genome, and CAT EUSAindicated that CAT protein was stably expressed in the cells. The introduced HBsAg DNA and HBsAgprotein expression were stably maintained for at least 60 generations in media devoid of chloramphenicol.This is the first report of the stable expression of foreign genes in D. salina.
文摘Background Awareness under general anesthesia is a serious complication which leads to psychiatric disorders. The incidence of awareness in patients undergoing cardiac surgery has been reported in as many as 1.5%-23% in foreign countries. But so far, medical literature about awareness during cardiac surgery is still rare in China. Therefore, we investigated the incidence of awareness in patients undergoing different kinds of cardiac surgery, the phases when awareness occured and the effect of cardiopulmonary bypass on the incidence of awareness in coronary artery bypass grafting in Beijing.Methods Patients' recall of awareness during cardiac surgery was assessed. One hundred patients undergoing coronary artery bypass grafting (CABG) in Chaoyang Hospital, Beijing, one hundred patients undergoing CABG and one hundred patients undergoing valve replacement or septal defect repair in Fuwai Hospital, Beijing, were interviewed 3-6 days after surgery. Every report obout patients on recall of awareness was recorded. An independent research team, blinded to patients' surgery and anesthesia, assessed every report of awareness.Results The incidence of awareness of patients received CABG under cardiopulmonary bypass (CPB), off -pump CABG, septal repair or valve replacement under CPB was 4.7% (5 of 106 cases), 9.6% (9 of 94 cases) and 4% (4 of 100 cases), respectively. CPB did not greatly affect the incidence of awareness during the period of CABG (P>0.05). The incidence of awareness of patients who received CABG under CPB did not increase significantly, in comparison with that of patients who received septal repair or valve replacement under CPB in Fuwai Hospital (P>0.05). Awareness easily occurred before bypass grafting or CPB.Conclusions Awareness mainly occurs before bypass grafting or CPB in cardiac surgery. Most cases with awareness have auditory perceptions. CPB is not a main factor which affects the incidence of awareness of CABG. Surgical types do not affect the incidence of awareness of patients under CPB.
文摘针对单声矢量传感器(Acoustic vector sensor,AVS)脉冲噪声环境下的多声源波达方向(Direction of arrival,DOA)跟踪问题,利用α稳定分布能更好地建模脉冲噪声的性质,提出α稳定分布下的多伯努利DOA跟踪算法。由于α稳定分布不具有有限协方差,该算法采用分数低阶距(Fractional Lower Order Moment,FLOM)代替协方差矩阵,对FLOM进行特征分解构造噪声子空间,生成FLOM-MUSIC空间谱函数作为多伯努利滤波器的伪似然函数,并对其指数加权,改善了传统似然函数的发散和平坦问题,使得粒子的重采样更有效。该算法的优点是不需要预先知道声源个数,利用先验信息和当前量测信息可以直接对当前声源进行跟踪。仿真结果表明,该算法能有效跟踪脉冲噪声环境下单一AVS声源的数目和状态。
文摘针对目标检测概率较低导致单个传感器无法对目标进行有效检测并跟踪的问题,本文提出了多传感器箱粒子概率假设密度(multi-sensor box particle probability hypothesis density filter,MS-BOX-PHD)滤波器。MS-BOX-PHD滤波器首先将多个传感器的量测转换、融合成为一个量测集合,并利用箱粒子概率假设密度(box particle probability hypothesis density filter,BOX-PHD)滤波器对多个目标的状态进行预测和更新。数值实验表明,相较于单传感器箱粒子概率假设密度(Single-BOX-PHD)滤波器,MS-BOX-PHD滤波器在目标检测概率较低时,能够有效地对多目标的状态和数目进行估计;相较于区间量测下多传感器标准PHD粒子(multi-sensor standard probability hypothesis density particle filter with interval measurement,IM-PHD-PF)滤波器,在达到相同的跟踪性能时,计算效率提升了38.57%。