1文献类型治疗2证据水平1b3文献来源Wu Y L, Huang Z F, Wang S Y, et al. A randomi-zed trial of systematic nodal dissection in resectablenon-small cell lung cancer [J]. Lung Cancer,2002,36(1)
A 16bit sigma-delta audio analog-to-digital converter is developed.It consists of an analog modulator and a digital decimator.A standard 2-order single-loop architecture is employed in the modulator.Chopper stabilizat...A 16bit sigma-delta audio analog-to-digital converter is developed.It consists of an analog modulator and a digital decimator.A standard 2-order single-loop architecture is employed in the modulator.Chopper stabilization is applied to the first integrator to eliminate the 1/f noise.A low-power,area-efficient decimator is used,which includes a poly-phase comb-filter and a wave-digital-filter.The converter achieves a 92dB dynamic range over the 96kHz audio band.This single chip occupies 2.68mm2 in a 0.18μm six-metal CMOS process and dissipates only 15.5mW power.展开更多
In order to predict the extreme load of the mechanical components during the entire life,an automatic method based on the bootstrapping technology(BT)is proposed to determine the most suitable threshold.Based on all t...In order to predict the extreme load of the mechanical components during the entire life,an automatic method based on the bootstrapping technology(BT)is proposed to determine the most suitable threshold.Based on all the turning points of the load history and a series of thresholds estimated in advance,the generalized Pareto distribution is established to fit the exceedances.The corresponding distribution parameters are estimated with the maximum likelihood method.Then,BT is employed to calculate the mean squared error(MSE)of each estimated threshold based on the exceedances and the specific distribution parameters.Finally,the threshold with the smallest MSE will be the optimal one.Compared to the kurtosis method and the mean excess function method,the average deviation of the probability density function of exceedances determined by BT reduces by 38.52%and 29.25%,respectively.Moreover,the quantile-quantile plot of the exceedances determined by BT is closer to a straight line.The results suggest the improvement of the modeling flexibility and the determined threshold precision.If the exceedances are insufficient,BT will enlarge their amount by resampling to solve the instability problem of the original distribution parameters.展开更多
Soil samples were collected from both bare and vegetated mine railings to study the changes in bacterial communities and soil chemical properties of copper mine tailings due to reed （Phragmites communis） colonizatio...Soil samples were collected from both bare and vegetated mine railings to study the changes in bacterial communities and soil chemical properties of copper mine tailings due to reed （Phragmites communis） colonization. The structures of bacterial communities were investigated using culture-independent 16S rRNA gene sequencing method. The bacterial diversity in the bare mine tailing was lower than that of the vegetated mine tailing. The former was dominated by sulfur metabolizing bacteria, whereas the latter was by nitrogen fixing bacteria. The bare mine tailing was acidic （pH = 3.78）, whereas the vegetated mine tailing was near neutral （pH ： 7.28）. The contents of organic matter, total nitrogen, and ammonium acetate-extractable potassium in vegetated mine tailings were significantly higher than those in the bare mine railings （P 〈 0.01）, whereas available phosphorus and electrical conductivity were significantly lower than those in the bare mine tailings （P 〈 0.01）. The results demonstrated that 16S rRNA gene sequencing could be successfully used to study the bacterial diversity in mine tailings. The colonization of the mine tailings by reed significantly changed the bacterial community and the chemical properties of tailings. The complex interactions between bacteria and plants deserve further investigation.展开更多
Biliary strictures are considered indeterminate when basic work-up, including transabdominal imaging and endoscopic retrograde cholangiopancreatography with routine cytologic brushing, are non-diagnostic. Indeterminat...Biliary strictures are considered indeterminate when basic work-up, including transabdominal imaging and endoscopic retrograde cholangiopancreatography with routine cytologic brushing, are non-diagnostic. Indeterminate biliary strictures can easily be mischaracterized which may dramatically affect patient's outcome. Early and accurate diagnosis of malignancy impacts not only a patient's candidacy for surgery, but also potential timely targeted chemotherapies. A significant portion of patients with indeterminate biliary strictures have benign disease and accurate diagnosis is, thus, paramount to avoid unnecessary surgery. Current sampling strategies have suboptimal accuracy for the diagnosis of malignancy. Emerging data on other diagnostic modalities, such as ancillary cytology techniques, single operator cholangioscopy, and endoscopic ultrasonography-guided fine needle aspiration, revealed promising results with much improved sensitivity.展开更多
Solid phase microextraction （SPME） is a solvent-flee method of sample collection. SPME is an appealing method for sample collection because it is designed for the sampling of trace level analytes with short sampling...Solid phase microextraction （SPME） is a solvent-flee method of sample collection. SPME is an appealing method for sample collection because it is designed for the sampling of trace level analytes with short sampling times in a variety of environments. Additionally, SPME can be used to directly deliver a sample to a gas chromatograph （GC） for analysis by means of thermal desorption. In this paper, the performance of SPME under dynamic conditions was investigated. Additionally, the competence of SPME sampling for the simultaneous analysis of multiple trace analytes was also evaluated. This work is discussed in the context of underground mine ventilation surveys but is applicable to any industry in which ventilation circuits must be evaluated. The results of this paper showed that the performance of the 100 ~m PDMS SPME fiber was both precise and rapid under dynamic conditions. This SPME fiber was also able to simultaneously collect sulfur hexafluoride （SF6） and perfluoromethylcyclohexane （PMCH） with adequate sensitivity.展开更多
This paper presents an assessment of air quality of the Kathmandu valley, capital city of Nepal. This is the largest urbanized area in the country of about 300 km2. In the last two decades an intensive development of ...This paper presents an assessment of air quality of the Kathmandu valley, capital city of Nepal. This is the largest urbanized area in the country of about 300 km2. In the last two decades an intensive development of demographic, traffic and industry growth in the region was observed which was reflected on the air quality degradation. In order to evaluate the urban air quality in Kathmandu, a field monitoring network for particle deposition, nitrogen dioxide （NO2） and sulphur dioxide （SO2） by passive sampling with high space resolution was implemented in co-operation with IVL-Sweden. The net work composed of 60 monitoring sites distributed in a grid of 1 × 1 km2 covering all over the main city and some rural valley. Monitoring were carried out for two seasons, rainy and dry as two campaign monitoring. The diffusive samplers were prepared and analyzed in IVL, Sweden. Good agreements in particle deposition between the two campaigns were observed. The particle deposition to the surrogate surface varied between 3 and 608 μg@cm2·monthl for the monitoring periods. The NOz concentrations on the other hand were quite similar in the two campaigns, and the SO2 concentrations were much lower in the first campaign compared to the second. The ranges of NO2 and SO2 concentrations were found to be from 5.6 to 52.6 μg/m3 and 0.6 to 23.4 μg·m-3 respectively. Arc Info/Arc map GIS 9.2 software was used for production of maps of spatial distribution of all the three parameters in the valley. Seasonal variation and traffic influence were also studied. Local meteorological effects in the distribution of pollutants were clearly observed and the NO2 concentrations were strictly related with traffic intensity.展开更多
Developing nations, like Nigeria, whose financial systems and infrastructural base are not yet fully developed face data rendition challenges which may hamper the representativeness of their interest rate statistics.A...Developing nations, like Nigeria, whose financial systems and infrastructural base are not yet fully developed face data rendition challenges which may hamper the representativeness of their interest rate statistics.A critical component of any credible interest rate data compilation framework relates to the sampling procedure.In Nigeria, no work has been done with regards to employing alternatives sampling techniques in the computation of interest rate statistics largely because of the small number of deposit money banks in the country. Leveraging on existing literature and established statistical methods, the study examines two sampling techniques for generating credible and reliable interest rates in Nigeria. The current interest rate compilation framework in the country is presented and alternative sampling procedures were explored with a view to investigating their appropriateness for Nigeria＇s interest rate computation. The interest rates generated based on the current population-based compilation method is compared with those of the alternative approaches. This paper recommends the use of purposive sampling method that covers Deposit Money Banks （DMBs） which account for about 70.0 per cent of the banking sector total assets as an appropriatealternative.展开更多
This article aims to describe the perception of the residents of Tepoztlan Morelos regarding the level of employment since their designation as Magic Town. Tepoztlan is a municipality in the northern part of the State...This article aims to describe the perception of the residents of Tepoztlan Morelos regarding the level of employment since their designation as Magic Town. Tepoztlan is a municipality in the northern part of the State of Morelos, located in the South-Central of Mexico. It is a magical town situated on the slopes of the Tepozteco Mountain. It is recognized as one of the most attractive places in the aforementioned state. Its relative proximity to Mexico City makes this town an attractive tourist destination for visitors. The importance of this issue lies mainly in the fact that tourism is one of the largest sources of income and employment generation for the country, so it is essential to strengthen the tourism infrastructure through federal programs of social participation, which promotes the development from the bottom to top. With that objective, the Mexican government created a federal program primarily with the purpose of contributing to the development of rural tourism. So, the ＂Magic Towns＂ program emerged as a strategy to generate resources for certain communities and increase the tourist offer. Tepoztlan was one of the first towns to enter the program, so it is relevant to analyze if the benefits generated by this program related to employment are perceived by the population. That is to say, to know the opinion of the settlers on the increase and the conditions of the employment that tourism generates and how the denomination of magical town influences this. Regarding the method used, we can say that it is a research with a quantitative approach, a questionnaire was designed as an instrument for data collection. The sample was obtained by the sampling method called： simple random probabilistic sampling. The results presented here correspond to a sample of 119 inhabitants of Tepoztlan. In summary, the research on this subject allows us to conclude that there is an increase in the generation of jobs in Tepoztl/m since its denomination as Magical Town; however, the working conditions and remuneration generated by tourism are perceived as low and far from the expectations of the population.展开更多
Based on the 454 pyrosequencing approach, this research evaluated the influence of coal mining subsi- dence on soil bacterial diversity and community structure in Chinese mining area. In order to characterize the bact...Based on the 454 pyrosequencing approach, this research evaluated the influence of coal mining subsi- dence on soil bacterial diversity and community structure in Chinese mining area. In order to characterize the bacterial community comparatively, this study selected a field experiment site with coal-excavated subsidence soils and an adjacent site with non-disturbed agricultural soils, respectively. The dataset com- prises 24512 sequences that are affiliated to the 7 phylogenetic groups： proteobacteria, actinobacteria, bacteroidetes, gemmatimonadetes, chlorofiexi, nitrospirae and unclassified phylum. Proteobacteria is the largest bacterial phylum in all samples, with a marked shift of the proportions of alpha-, beta-, and gammaproteobacteria. The results show that undisturbed soils are relatively more diverse and rich than subsided soils, and differences in abundances of dominant taxonomic groups between the two soil groups are visible. Compared with the control, soil nutrient contents decline achieves significant level in subsided soils. Correlational analysis showed bacterial diversity indices have significantly positive corre- lation with soil organic matter, total N, total P, and available K. but in negative relation with soil salinity. Ground subsidence noticeably affects the diversity and composition of soil microbial community. Degen- eration of soil fertility and soil salinization inhibits the sole-carbon-source metabolic ability of microbial community, leading to the simplification of advantage species and uneven distribution of microbial spe- cies. This work demonstrates the great potential of pyrosequencing technique in revealing microbial diversity and presents background information of microbial communities of mine subsidence land.展开更多
文摘1文献类型治疗2证据水平1b3文献来源Wu Y L, Huang Z F, Wang S Y, et al. A randomi-zed trial of systematic nodal dissection in resectablenon-small cell lung cancer [J]. Lung Cancer,2002,36(1)
文摘A 16bit sigma-delta audio analog-to-digital converter is developed.It consists of an analog modulator and a digital decimator.A standard 2-order single-loop architecture is employed in the modulator.Chopper stabilization is applied to the first integrator to eliminate the 1/f noise.A low-power,area-efficient decimator is used,which includes a poly-phase comb-filter and a wave-digital-filter.The converter achieves a 92dB dynamic range over the 96kHz audio band.This single chip occupies 2.68mm2 in a 0.18μm six-metal CMOS process and dissipates only 15.5mW power.
基金The National Science and Technology Pillar Program of China(No.2015BAF07B00)
文摘In order to predict the extreme load of the mechanical components during the entire life,an automatic method based on the bootstrapping technology(BT)is proposed to determine the most suitable threshold.Based on all the turning points of the load history and a series of thresholds estimated in advance,the generalized Pareto distribution is established to fit the exceedances.The corresponding distribution parameters are estimated with the maximum likelihood method.Then,BT is employed to calculate the mean squared error(MSE)of each estimated threshold based on the exceedances and the specific distribution parameters.Finally,the threshold with the smallest MSE will be the optimal one.Compared to the kurtosis method and the mean excess function method,the average deviation of the probability density function of exceedances determined by BT reduces by 38.52%and 29.25%,respectively.Moreover,the quantile-quantile plot of the exceedances determined by BT is closer to a straight line.The results suggest the improvement of the modeling flexibility and the determined threshold precision.If the exceedances are insufficient,BT will enlarge their amount by resampling to solve the instability problem of the original distribution parameters.
基金the National Natural Science Foundation of China (Nos.39830310 and 30070134)the NationalKey Basic Research Support Foundation (NKBRSF) of China (No.2002CB111504).
文摘Soil samples were collected from both bare and vegetated mine railings to study the changes in bacterial communities and soil chemical properties of copper mine tailings due to reed （Phragmites communis） colonization. The structures of bacterial communities were investigated using culture-independent 16S rRNA gene sequencing method. The bacterial diversity in the bare mine tailing was lower than that of the vegetated mine tailing. The former was dominated by sulfur metabolizing bacteria, whereas the latter was by nitrogen fixing bacteria. The bare mine tailing was acidic （pH = 3.78）, whereas the vegetated mine tailing was near neutral （pH ： 7.28）. The contents of organic matter, total nitrogen, and ammonium acetate-extractable potassium in vegetated mine tailings were significantly higher than those in the bare mine railings （P 〈 0.01）, whereas available phosphorus and electrical conductivity were significantly lower than those in the bare mine tailings （P 〈 0.01）. The results demonstrated that 16S rRNA gene sequencing could be successfully used to study the bacterial diversity in mine tailings. The colonization of the mine tailings by reed significantly changed the bacterial community and the chemical properties of tailings. The complex interactions between bacteria and plants deserve further investigation.
文摘Biliary strictures are considered indeterminate when basic work-up, including transabdominal imaging and endoscopic retrograde cholangiopancreatography with routine cytologic brushing, are non-diagnostic. Indeterminate biliary strictures can easily be mischaracterized which may dramatically affect patient's outcome. Early and accurate diagnosis of malignancy impacts not only a patient's candidacy for surgery, but also potential timely targeted chemotherapies. A significant portion of patients with indeterminate biliary strictures have benign disease and accurate diagnosis is, thus, paramount to avoid unnecessary surgery. Current sampling strategies have suboptimal accuracy for the diagnosis of malignancy. Emerging data on other diagnostic modalities, such as ancillary cytology techniques, single operator cholangioscopy, and endoscopic ultrasonography-guided fine needle aspiration, revealed promising results with much improved sensitivity.
基金Contract No.200-2009-31933,awarded by the National Institute for Occupational Safety and Health(NIOSH)
文摘Solid phase microextraction （SPME） is a solvent-flee method of sample collection. SPME is an appealing method for sample collection because it is designed for the sampling of trace level analytes with short sampling times in a variety of environments. Additionally, SPME can be used to directly deliver a sample to a gas chromatograph （GC） for analysis by means of thermal desorption. In this paper, the performance of SPME under dynamic conditions was investigated. Additionally, the competence of SPME sampling for the simultaneous analysis of multiple trace analytes was also evaluated. This work is discussed in the context of underground mine ventilation surveys but is applicable to any industry in which ventilation circuits must be evaluated. The results of this paper showed that the performance of the 100 ~m PDMS SPME fiber was both precise and rapid under dynamic conditions. This SPME fiber was also able to simultaneously collect sulfur hexafluoride （SF6） and perfluoromethylcyclohexane （PMCH） with adequate sensitivity.
文摘This paper presents an assessment of air quality of the Kathmandu valley, capital city of Nepal. This is the largest urbanized area in the country of about 300 km2. In the last two decades an intensive development of demographic, traffic and industry growth in the region was observed which was reflected on the air quality degradation. In order to evaluate the urban air quality in Kathmandu, a field monitoring network for particle deposition, nitrogen dioxide （NO2） and sulphur dioxide （SO2） by passive sampling with high space resolution was implemented in co-operation with IVL-Sweden. The net work composed of 60 monitoring sites distributed in a grid of 1 × 1 km2 covering all over the main city and some rural valley. Monitoring were carried out for two seasons, rainy and dry as two campaign monitoring. The diffusive samplers were prepared and analyzed in IVL, Sweden. Good agreements in particle deposition between the two campaigns were observed. The particle deposition to the surrogate surface varied between 3 and 608 μg@cm2·monthl for the monitoring periods. The NOz concentrations on the other hand were quite similar in the two campaigns, and the SO2 concentrations were much lower in the first campaign compared to the second. The ranges of NO2 and SO2 concentrations were found to be from 5.6 to 52.6 μg/m3 and 0.6 to 23.4 μg·m-3 respectively. Arc Info/Arc map GIS 9.2 software was used for production of maps of spatial distribution of all the three parameters in the valley. Seasonal variation and traffic influence were also studied. Local meteorological effects in the distribution of pollutants were clearly observed and the NO2 concentrations were strictly related with traffic intensity.
文摘Developing nations, like Nigeria, whose financial systems and infrastructural base are not yet fully developed face data rendition challenges which may hamper the representativeness of their interest rate statistics.A critical component of any credible interest rate data compilation framework relates to the sampling procedure.In Nigeria, no work has been done with regards to employing alternatives sampling techniques in the computation of interest rate statistics largely because of the small number of deposit money banks in the country. Leveraging on existing literature and established statistical methods, the study examines two sampling techniques for generating credible and reliable interest rates in Nigeria. The current interest rate compilation framework in the country is presented and alternative sampling procedures were explored with a view to investigating their appropriateness for Nigeria＇s interest rate computation. The interest rates generated based on the current population-based compilation method is compared with those of the alternative approaches. This paper recommends the use of purposive sampling method that covers Deposit Money Banks （DMBs） which account for about 70.0 per cent of the banking sector total assets as an appropriatealternative.
文摘This article aims to describe the perception of the residents of Tepoztlan Morelos regarding the level of employment since their designation as Magic Town. Tepoztlan is a municipality in the northern part of the State of Morelos, located in the South-Central of Mexico. It is a magical town situated on the slopes of the Tepozteco Mountain. It is recognized as one of the most attractive places in the aforementioned state. Its relative proximity to Mexico City makes this town an attractive tourist destination for visitors. The importance of this issue lies mainly in the fact that tourism is one of the largest sources of income and employment generation for the country, so it is essential to strengthen the tourism infrastructure through federal programs of social participation, which promotes the development from the bottom to top. With that objective, the Mexican government created a federal program primarily with the purpose of contributing to the development of rural tourism. So, the ＂Magic Towns＂ program emerged as a strategy to generate resources for certain communities and increase the tourist offer. Tepoztlan was one of the first towns to enter the program, so it is relevant to analyze if the benefits generated by this program related to employment are perceived by the population. That is to say, to know the opinion of the settlers on the increase and the conditions of the employment that tourism generates and how the denomination of magical town influences this. Regarding the method used, we can say that it is a research with a quantitative approach, a questionnaire was designed as an instrument for data collection. The sample was obtained by the sampling method called： simple random probabilistic sampling. The results presented here correspond to a sample of 119 inhabitants of Tepoztlan. In summary, the research on this subject allows us to conclude that there is an increase in the generation of jobs in Tepoztl/m since its denomination as Magical Town; however, the working conditions and remuneration generated by tourism are perceived as low and far from the expectations of the population.
基金supported by the National Natural Science Foundation of China (No. 51174207)Priority Academic Program Development (PAPD) of Jiangsu Higher Education Institutions of China (No. SZBF20116B35)
文摘Based on the 454 pyrosequencing approach, this research evaluated the influence of coal mining subsi- dence on soil bacterial diversity and community structure in Chinese mining area. In order to characterize the bacterial community comparatively, this study selected a field experiment site with coal-excavated subsidence soils and an adjacent site with non-disturbed agricultural soils, respectively. The dataset com- prises 24512 sequences that are affiliated to the 7 phylogenetic groups： proteobacteria, actinobacteria, bacteroidetes, gemmatimonadetes, chlorofiexi, nitrospirae and unclassified phylum. Proteobacteria is the largest bacterial phylum in all samples, with a marked shift of the proportions of alpha-, beta-, and gammaproteobacteria. The results show that undisturbed soils are relatively more diverse and rich than subsided soils, and differences in abundances of dominant taxonomic groups between the two soil groups are visible. Compared with the control, soil nutrient contents decline achieves significant level in subsided soils. Correlational analysis showed bacterial diversity indices have significantly positive corre- lation with soil organic matter, total N, total P, and available K. but in negative relation with soil salinity. Ground subsidence noticeably affects the diversity and composition of soil microbial community. Degen- eration of soil fertility and soil salinization inhibits the sole-carbon-source metabolic ability of microbial community, leading to the simplification of advantage species and uneven distribution of microbial spe- cies. This work demonstrates the great potential of pyrosequencing technique in revealing microbial diversity and presents background information of microbial communities of mine subsidence land.
