Introduction: Infectious diseases constitute a major concern of public health in developing countries. Facilities and well trained staff have been shown to be one of the major obstacles in the rapid and quality diagno...Introduction: Infectious diseases constitute a major concern of public health in developing countries. Facilities and well trained staff have been shown to be one of the major obstacles in the rapid and quality diagnosis of these diseases. As such, we carried out an analysis to compare the Widal test and stool culture to identify febrile patients with Salmonella infection. Method: A cross sectional study was conducted to diagnose salmonella infection with out-patients who demonstrated signs of salmonella infection. Serum was harvested from blood collected from 368 (Vina = 234, Mayo Banyo 65, and Djerem = 69) patients accompanied by stool, Widal test was conducted on the spot and stool was taken to a reference laboratory for culture using standard microbiological methods, sociological set up was calculated in percentages, prevalence was calculated using excel while statistical difference was calculated using SPSS. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated to compare the Widal test against stool culture. Results: A total of 368 (50.8% females and 49.2% males) participants took part in the survey. Salmonella prevalence (66.24%) in stool culture in the Vina division was significantly different (p 0.05). The sensitivity,specificity, PPV, and NPV of slide agglutination test against stool culture varied from different areas (Vina: 51.6%, 73.62%, 79.21% and 43.61%;Mayo Banyo: 60.53%, 77.78%, 79.31% and 58.33%;Djerem: 53.18%, 83.73% 73.91% and 67.39%) respectively. Slide agglutination test has a fair agreement with the stool culture (kappa, Vina = 0.202;Mayo Banyo = 0.37 and Djerem = 0.38). Conclusion: Generally, in the three areas of study, the Widal test had a fair correlation with the stool culture;This means the Widal test should not be used alone but in combination with stool culture in the detection of salmonella infections.展开更多
For optimal design of constant stress accelerated life test(CSALT) with two-stress, if the stresses could not reach the highest levels simultaneously, the test region becomes non-rectangular. For optimal CSALT desig...For optimal design of constant stress accelerated life test(CSALT) with two-stress, if the stresses could not reach the highest levels simultaneously, the test region becomes non-rectangular. For optimal CSALT design on non-rectangle test region, the present method is only focused on non-rectangle test region with simple boundary, and the optimization algorithm is based on experience which can not ensure to obtain the optimal plan. In this paper, considering the linear-extreme value model and the optimization goal to minimize the variance of lifetime estimate under normal stress, the optimal design method of two-stress type-I censored CSALT plan on general non-rectangular test region is proposed. First, two properties of optimal test plans are proved and the relationship of all the optimal test plans is determined analytically. Then, on the basis of the two properties, the optimal problem is simplified and the optimal design method of two-stress CSALT plan on general non-rectangular test region is proposed. Finally, a numerical example is used to illustrate the feasibility and effectiveness of the method, The result shows that the proposed method could obtain the optimal test plan on non-rectangular test regions with arbitrary boundaries. This research provides the theory and method for two-stress optimal CSALT planning on non-rectangular test regions.展开更多
This study addresses the changes in acceleration,pore water pressure and Fourier spectrums of different types of seismic waves with various amplitudes via large-scale shaking table tests from two sites:a sand-containi...This study addresses the changes in acceleration,pore water pressure and Fourier spectrums of different types of seismic waves with various amplitudes via large-scale shaking table tests from two sites:a sand-containing regional site and an all-clay site.Comparative analyses of the test results show that the pore water pressures in sand-soil layers of the regional site initially increase and then decrease as the amplitudes of the seismic accelerations increase.The actions of the vertical and vibrational seismic waves contribute to greater pore water pressures.The amplification coefficient of the sand-layer regional site becomes smaller as the seismic waves grow stronger,so that both sites are capable of filtering high frequencies and amplifying low frequencies of seismic waves.This is more apparent with the increase in the peak value of the acceleration,and the natural vibration frequencies of both sites decrease with the transmission of the seismic waves from the basement to the ground surface.The decreasing frequency value of the sand-containing regional site is smaller than that of the all-clay site.展开更多
Based on the similarity theory, taking the horseshoe, city-gate and round linings as examples, the value and distribution regularities of normal frost heaving pressures (hereinafter as frost heaving pressures) in tu...Based on the similarity theory, taking the horseshoe, city-gate and round linings as examples, the value and distribution regularities of normal frost heaving pressures (hereinafter as frost heaving pressures) in tunnels excavated in fractured rock mass in cold regions under different constraints and freezing depths were studied by a test model. It was found that the larger the frozen depth, the larger the frost heaving pressure, and the stronger the top constraint, the larger the frost heaving pressure. For the horseshoe lining and city-gate lining, the top constraint has a greater effect on the frost heaving pressures on the arch and the inverted arch. For the round lining, the influences of the top constraint on the frost heaving pressure in all linings are almost the same. The frost heaving pressure is maximum on the city-gate lining and minimal on the round lining. The largest frost heaving pressure all occur near the foot of the inverted arch for the three kinds of lining. Thus, the test data basically coincide with the observed in situ data.展开更多
The West Development Policy being implemented in China is causing significant land use and land cover (LULC) changes in West China. With the up-to-date satellite database of the Global Land Cover Characteristics Dat...The West Development Policy being implemented in China is causing significant land use and land cover (LULC) changes in West China. With the up-to-date satellite database of the Global Land Cover Characteristics Database (GLCCD) that characterizes the lower boundary conditions, the regional climate model RIEMS-TEA is used to simulate possible impacts of the significant LULC variation. The model was run for five continuous three-month periods from 1 June to 1 September of 1993, 1994, 1995, 1996, and 1997, and the results of the five groups are examined by means of a student t-test to identify the statistical significance of regional climate variation. The main results are: (1) The regional climate is affected by the LULC variation because the equilibrium of water and heat transfer in the air-vegetation interface is changed. (2) The integrated impact of the LULC variation on regional climate is not only limited to West China where the LULC varies, but also to some areas in the model domain where the LULC does not vary at all. (3) The East Asian monsoon system and its vertical structure are adjusted by the large scale LULC variation in western China, where the consequences are the enhancement of the westward water vapor transfer from the east oast and the relevant increase of wet-hydrostatic energy in the middle-upper atmospheric layers. (4) The ecological engineering in West China affects significantly the regional climate in Northwest China, North China and the middle-lower reaches of the Yangtze River; there are obvious effects in South, Northeast, and Southwest China, but minor effects in Tibet.展开更多
High concentrated and heterogeneous distribution of gas hydrates have been identified in the gas hydrate production test region in the Shenhu area,South China Sea.The gas hydrate-bearing sediments with high saturation...High concentrated and heterogeneous distribution of gas hydrates have been identified in the gas hydrate production test region in the Shenhu area,South China Sea.The gas hydrate-bearing sediments with high saturation locate at two ridges of submarine canyon with different thickness and saturations just above the bottom simulating reflection.The crossplots of gamma ray,acoustic impedance(P-impedance)and porosity at four sites show that the sediments can be divided into the upper and lower layers at different depths,indicating different geotechnical reservoir properties.Therefore,the depositional environments and physical properties at two ridges are analyzed and compared to show the different characteristics of hydrate reservoir.High porosity,high P-wave velocity,and coarse grain size indicate better reservoir quality and higher energy depositional environment for gas hydrate at Sites W18 and W19 than those at Sites W11 and W17.Our interpretation is that the base of canyon deposits at Sites W18 and W19 characterized by upward-coarsening units may be turbidity sand layers,thus significantly improving the reservoir quality with increasing gas hydrate saturation.The shelf and slope sliding deposits compose of the fine-grained sediments at Sites W11 and W17.The gas hydrate production test sites were conducted at the ridge of W11 and W17,mainly because of the thicker and larger area of gas hydrate-bearing reservoirs than those at Sites W18 and W19.All the results provide useful insights for assessing reservoir quality in the Shenhu area.展开更多
文摘Introduction: Infectious diseases constitute a major concern of public health in developing countries. Facilities and well trained staff have been shown to be one of the major obstacles in the rapid and quality diagnosis of these diseases. As such, we carried out an analysis to compare the Widal test and stool culture to identify febrile patients with Salmonella infection. Method: A cross sectional study was conducted to diagnose salmonella infection with out-patients who demonstrated signs of salmonella infection. Serum was harvested from blood collected from 368 (Vina = 234, Mayo Banyo 65, and Djerem = 69) patients accompanied by stool, Widal test was conducted on the spot and stool was taken to a reference laboratory for culture using standard microbiological methods, sociological set up was calculated in percentages, prevalence was calculated using excel while statistical difference was calculated using SPSS. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated to compare the Widal test against stool culture. Results: A total of 368 (50.8% females and 49.2% males) participants took part in the survey. Salmonella prevalence (66.24%) in stool culture in the Vina division was significantly different (p 0.05). The sensitivity,specificity, PPV, and NPV of slide agglutination test against stool culture varied from different areas (Vina: 51.6%, 73.62%, 79.21% and 43.61%;Mayo Banyo: 60.53%, 77.78%, 79.31% and 58.33%;Djerem: 53.18%, 83.73% 73.91% and 67.39%) respectively. Slide agglutination test has a fair agreement with the stool culture (kappa, Vina = 0.202;Mayo Banyo = 0.37 and Djerem = 0.38). Conclusion: Generally, in the three areas of study, the Widal test had a fair correlation with the stool culture;This means the Widal test should not be used alone but in combination with stool culture in the detection of salmonella infections.
基金supported by National Natural Science Foundation of China(Grant Nos. 50935002, 51075370, 51105341)National Hi-tech Research and Development Program of China(863 Program, Grant No. 2007AA04Z409)+1 种基金the Technology Foundation of National Defense ProgramZhejiang Provincial Natural Science Foundation of China (Grant Nos. Y1100777, Y1080762)
文摘For optimal design of constant stress accelerated life test(CSALT) with two-stress, if the stresses could not reach the highest levels simultaneously, the test region becomes non-rectangular. For optimal CSALT design on non-rectangle test region, the present method is only focused on non-rectangle test region with simple boundary, and the optimization algorithm is based on experience which can not ensure to obtain the optimal plan. In this paper, considering the linear-extreme value model and the optimization goal to minimize the variance of lifetime estimate under normal stress, the optimal design method of two-stress type-I censored CSALT plan on general non-rectangular test region is proposed. First, two properties of optimal test plans are proved and the relationship of all the optimal test plans is determined analytically. Then, on the basis of the two properties, the optimal problem is simplified and the optimal design method of two-stress CSALT plan on general non-rectangular test region is proposed. Finally, a numerical example is used to illustrate the feasibility and effectiveness of the method, The result shows that the proposed method could obtain the optimal test plan on non-rectangular test regions with arbitrary boundaries. This research provides the theory and method for two-stress optimal CSALT planning on non-rectangular test regions.
基金National Program on Key Basic Research Project(973 Program)under Grant No.2011CB013606Program for Changjiang Scholars and Innovative Research Team in University under Grant No.IRT13057+1 种基金Key Program of National Natural Science Foundation of China under Grant No.51438004the Research Fund for the Doctoral Program of Higher Education of China under Grant No.20124410110004
文摘This study addresses the changes in acceleration,pore water pressure and Fourier spectrums of different types of seismic waves with various amplitudes via large-scale shaking table tests from two sites:a sand-containing regional site and an all-clay site.Comparative analyses of the test results show that the pore water pressures in sand-soil layers of the regional site initially increase and then decrease as the amplitudes of the seismic accelerations increase.The actions of the vertical and vibrational seismic waves contribute to greater pore water pressures.The amplification coefficient of the sand-layer regional site becomes smaller as the seismic waves grow stronger,so that both sites are capable of filtering high frequencies and amplifying low frequencies of seismic waves.This is more apparent with the increase in the peak value of the acceleration,and the natural vibration frequencies of both sites decrease with the transmission of the seismic waves from the basement to the ground surface.The decreasing frequency value of the sand-containing regional site is smaller than that of the all-clay site.
文摘Based on the similarity theory, taking the horseshoe, city-gate and round linings as examples, the value and distribution regularities of normal frost heaving pressures (hereinafter as frost heaving pressures) in tunnels excavated in fractured rock mass in cold regions under different constraints and freezing depths were studied by a test model. It was found that the larger the frozen depth, the larger the frost heaving pressure, and the stronger the top constraint, the larger the frost heaving pressure. For the horseshoe lining and city-gate lining, the top constraint has a greater effect on the frost heaving pressures on the arch and the inverted arch. For the round lining, the influences of the top constraint on the frost heaving pressure in all linings are almost the same. The frost heaving pressure is maximum on the city-gate lining and minimal on the round lining. The largest frost heaving pressure all occur near the foot of the inverted arch for the three kinds of lining. Thus, the test data basically coincide with the observed in situ data.
文摘The West Development Policy being implemented in China is causing significant land use and land cover (LULC) changes in West China. With the up-to-date satellite database of the Global Land Cover Characteristics Database (GLCCD) that characterizes the lower boundary conditions, the regional climate model RIEMS-TEA is used to simulate possible impacts of the significant LULC variation. The model was run for five continuous three-month periods from 1 June to 1 September of 1993, 1994, 1995, 1996, and 1997, and the results of the five groups are examined by means of a student t-test to identify the statistical significance of regional climate variation. The main results are: (1) The regional climate is affected by the LULC variation because the equilibrium of water and heat transfer in the air-vegetation interface is changed. (2) The integrated impact of the LULC variation on regional climate is not only limited to West China where the LULC varies, but also to some areas in the model domain where the LULC does not vary at all. (3) The East Asian monsoon system and its vertical structure are adjusted by the large scale LULC variation in western China, where the consequences are the enhancement of the westward water vapor transfer from the east oast and the relevant increase of wet-hydrostatic energy in the middle-upper atmospheric layers. (4) The ecological engineering in West China affects significantly the regional climate in Northwest China, North China and the middle-lower reaches of the Yangtze River; there are obvious effects in South, Northeast, and Southwest China, but minor effects in Tibet.
基金Supported by the Key Special Project for Introduced Talents Team of Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou)(No.GML2019ZD0104)the National Natural Science Foundation of China(Nos.U19B2005,42076072)+1 种基金the Pilot National Laboratory for Marine Science and Technology(Qingdao)Initial Foundation(No.JCZX202019)the Research Start-up Funds of Zhufeng Scholars Program。
文摘High concentrated and heterogeneous distribution of gas hydrates have been identified in the gas hydrate production test region in the Shenhu area,South China Sea.The gas hydrate-bearing sediments with high saturation locate at two ridges of submarine canyon with different thickness and saturations just above the bottom simulating reflection.The crossplots of gamma ray,acoustic impedance(P-impedance)and porosity at four sites show that the sediments can be divided into the upper and lower layers at different depths,indicating different geotechnical reservoir properties.Therefore,the depositional environments and physical properties at two ridges are analyzed and compared to show the different characteristics of hydrate reservoir.High porosity,high P-wave velocity,and coarse grain size indicate better reservoir quality and higher energy depositional environment for gas hydrate at Sites W18 and W19 than those at Sites W11 and W17.Our interpretation is that the base of canyon deposits at Sites W18 and W19 characterized by upward-coarsening units may be turbidity sand layers,thus significantly improving the reservoir quality with increasing gas hydrate saturation.The shelf and slope sliding deposits compose of the fine-grained sediments at Sites W11 and W17.The gas hydrate production test sites were conducted at the ridge of W11 and W17,mainly because of the thicker and larger area of gas hydrate-bearing reservoirs than those at Sites W18 and W19.All the results provide useful insights for assessing reservoir quality in the Shenhu area.