This study aimed to demonstrate change in spatial correlation between Korean pine (Pinus koraiensis Sieb. et Zucc.) and three rare species, and change in spatial distribution of four species in response to a range o...This study aimed to demonstrate change in spatial correlation between Korean pine (Pinus koraiensis Sieb. et Zucc.) and three rare species, and change in spatial distribution of four species in response to a range of selective cutting intensities. We sampled three plots of mixed Korean pine and broad-leaf forest in Lushuihe Forestry Bureau of Jilin province, China. Plot 1, a control, was unlogged Korean pine broad-leaf forest. In plots 2 and 3, Korean pine was selectively cut at 15 and 30 % intensity, respectively, in the 1970s. Other species were rarely cut. We used point-pattern analysis to research the spatial distributions of four tree species and quantify spatial correlations between Korean pine and the other three species, Amur linden (Tilia amurensis Rupr.), Manchurian ash (Fraxinus mandshurica Rupr.), and Mongolian oak (Quercus mongolica Fisch.) in all three plots. The results of the study show that selective cutting at 15 % intensity did not significantly change either the species spatial patterns or the spatial correlation between Korean pine and broadleaf species. Selective cutting at 30 % intensity slightly affected the growth of Korean pine and valuable species in forest communities, and the effect was considered nondestructive and recoverable.展开更多
With the continuous development of urbanization in China,the country’s growing population brings great challenges to urban development.By mastering the refined population spatial distribution in administrative units,...With the continuous development of urbanization in China,the country’s growing population brings great challenges to urban development.By mastering the refined population spatial distribution in administrative units,the quantity and agglomeration of population distribution can be estimated and visualized.It will provide a basis for a more rational urban planning.This paper takes Beijing as the research area and uses a new Luojia1-01 nighttime light image with high resolution,land use type data,Points of Interest(POI)data,and other data to construct the population spatial index system,establishing the index weight based on the principal component analysis.The comprehensive weight value of population distribution in the study area was then used to calculate the street population distribution of Beijing in 2018.Then the population spatial distribution was visualize using GIS technology.After accuracy assessments by comparing the result with the WorldPop data,the accuracy has reached 0.74.The proposed method was validated as a qualified method to generate population spatial maps.By contrast of local areas,Luojia 1-01 data is more suitable for population distribution estimation than the NPP/VIIRS(Net Primary Productivity/Visible infrared Imaging Radiometer)nighttime light data.More geospatial big data and mathematical models can be combined to create more accurate population maps in the future.展开更多
For a better understanding of the deposition mechanism of thin films in SiCl4 source gas, we have measured the spatial distributions of SiCln (n=0-2) radicals in SICl4 radio frequency glow discharge plasma utilizing...For a better understanding of the deposition mechanism of thin films in SiCl4 source gas, we have measured the spatial distributions of SiCln (n=0-2) radicals in SICl4 radio frequency glow discharge plasma utilizing a mass spectrometer equipped with a movable gas sampling apparatus. The experimental results demonstrate that the relative densities of SiCln (n=0-2) radicals have peak values at the position of 10 mm above the powered electrode along the axial direction; the relative densities of the Si and SiCIn (n=1, 2) radicals have peak values at the positions of 27mm and 7 mm away from the axis along the radial direction, respectively. Generally speaking, in the whole SICl4 plasma bulk region, the relative density of Si is one order of magnitude higher than that of SICl, and the relative density of SiCl is several times higher than that of SICl2. This reveals that Si and SiCl may be the primary growth precursors in forming thin films.展开更多
The Zagros forests are a treasure of valuable oak forests, but they have been severely degraded from long-term misuse. Geographic information systems (GIS) and multi-criteria decision analysis (MCDA) have been inc...The Zagros forests are a treasure of valuable oak forests, but they have been severely degraded from long-term misuse. Geographic information systems (GIS) and multi-criteria decision analysis (MCDA) have been increasingly used to improve the management of vulnerable ecosystems to prevent further degradation and increase the sustainability of land use. This study presents a methodology to assess land suitability using remote sensing (RS) to obtain wall-to-wall data for the calculations, GIS to analyze the data, and MCDA to rank alternative land uses. The criteria and subcriteria affecting the suitability of land for different uses were identified and weighted using an analytic hierarchy process. Variables used as subcriteria were assessed using satellite data and other sources of information such as existing maps and field surveys. Numerical values for the subcriteria were classified, and each class was given a priority rating according to expert judgments. Based on the ratings and weights of the subcriteria, a priority map was created for each land use using the weighted linear combination method. The priority maps for different land uses were overlaid to obtain a preliminary land use map, which often indicated several simultaneous land uses for the same location. The preliminary map was further edited by removing unrealistic, mutually exclusive land-use combinations. The study tested and demonstrated the potential of integrating RS, G1S and MCDA techniques for solving complicated land allocation problems in forested regions using a scientifically sound and practical approach for efficient and sustainable allocation of forestland for different uses.展开更多
A novel method based on wavelength-multiplexed line-of-sight absorption and profile fitting for nonuniform flow field measurement is reported. A wavelength scanning combing laser temperature and current modulation WMS...A novel method based on wavelength-multiplexed line-of-sight absorption and profile fitting for nonuniform flow field measurement is reported. A wavelength scanning combing laser temperature and current modulation WMS scheme is used to implement the wavelength-multi- plexed-profile fitting method. Second harmonic (2f) signal of eight H20 transitions features near 7,170 cm^-1 are measured in one period using a single tunable diode laser. Spatial resolved temperature distribution upon a CH4/air premixed flat flame burner is obtained. The result validates the feasibility of strategy for non-uniform flow field diagnostics by means of WMS-2f TDLAS.展开更多
On the basis of the emission data of the industrial sulphur dioxide (SO_2) and observed climate fields over East Asia, the distribution of anthropogenic sulfate aerosol(SO_4~2-) with seasonal variation in the troposph...On the basis of the emission data of the industrial sulphur dioxide (SO_2) and observed climate fields over East Asia, the distribution of anthropogenic sulfate aerosol(SO_4~2-) with seasonal variation in the troposphere is simulated and analyzed by a regional sulfur transport model, and the direct radiative effects of SO_4~2- under different weather conditions are also calculated using the discrete ordinate method. The results show that the concentration of SO_4~2- has significant seasonal and spatial variations resulting from the effects of SO_2 emission source and precipitation and wind fields. Both the concentration of SO_2 and its radiative forcing have the largest values in October and the lowest in July. SO_4~2- causes the decrease of the radiation flux absorbed by earth-atmosphere and the cooling of air temperature by scattering more solar radiation back into space. Besides, the radiative and climatic effects of SO_4~2- are related to the types and height and optical thickness, etc., of the clouds.展开更多
Dynamic load imposed on the bridge by mov- ing vehicle depends on several bridge-vehicle parameters with various uncertainties. In the present paper, particle filter technique based on conditional probability has been...Dynamic load imposed on the bridge by mov- ing vehicle depends on several bridge-vehicle parameters with various uncertainties. In the present paper, particle filter technique based on conditional probability has been used to identify vehicle mass, suspension stiffness, and damping including tyre parameters from simulated bridge accelerations at different locations. A closed-form expres- sion is derived to generate independent response samples for the idealized bridge-vehicle coupled system consider- ing spatially non-homogeneous pavement unevenness. Thereafter, it is interfaced with the iterative process of particle filtering algorithm. The generated response sam- ples are contaminated by adding artificial noise in order to reflect field condition. The mean acceleration time history is utilized in particle filtering technique. The vehicle- imposed dynamic load is reconstructed with the identified parameters and compared with the simulated results. The present identification technique is examined in the presence of different levels of artificial noise with bridge response simulated at different locations. The effect of vehicle velocity, bridge surface roughness, and choice of prior probability density parameters on the efficiency of the method is discussed.展开更多
OBJECTIVE To investigate the effects of osthole on learning and memory impairment of AD mice induced by injection of Aβ25-35 and the content of Ca2+, GLU and Aβ1-42 in the brain tissue and peripheral blood. METHODS ...OBJECTIVE To investigate the effects of osthole on learning and memory impairment of AD mice induced by injection of Aβ25-35 and the content of Ca2+, GLU and Aβ1-42 in the brain tissue and peripheral blood. METHODS Mice were randomly assigned to sham operation, Aβ25-35, Aβ25-35+Ost-L,Aβ25-35+Ost-M, and Aβ25-35+Ost-H group. Water maze test was performed to assessing spatial learning ability of mice. It is determined that the MDA level and the activity of SOD in the brain tissue of mice in each group by colorimetry. The GLU kit and Ca2 +kit were used to detect the GLU, Ca2 +in tissue and serum. ELISA was used to detect the expression of Aβ1-42 in the hippocampus and serum of mice. HE staining and silver staining were used to detect neuron apoptosis and pathological changes in brain slices and so on. RESULTS(1) Effects of osthole on learning and memory: With the increase of training day,the escape latencies continuously reduced in each experimental group, the escape latencies of the model group was longer on the 1 st, 2 nd, 3 rd, and 5 thdays than the normal group, the difference was statistically significant(day 3 and 4: P<0.05, day 5: P<0.01);compared with the model group, the escaping latency on the 5 thday of the OST low-medium high-dose group was significantly shortened, which was statistically significant(P<0.05).(2) Effects on oxidative stresspathway: the SOD activity of AD mice in the hippocampus model group was lower than that in the normal group, which was statistically significant(P<0.05);The SOD activity in the OST group was higher than that in the model group, which was statistically significant(P<0.05). The MDA content in the model group was significantly higher than that in the normal group(P<0.05). The MDA content in the OST high-dose group was lower than that in the model group, which was statistically significant(P<0.05).(3) Effects of GLU levels on neurotransmitters:the results of the detection of GLU in cortical area and GLU in serum of AD mice in OST dose groups showed that serum GLU levels in the model group were significantly lower than those in the sham group, which was statistically significant(P<0.05). GLU levels in the cortical area were also significantly higher than those in the sham group, which was statistically significant(P<0.05). Compared with the model group, GLU levels in the OST administration group were significantly down-regulated. Among the serum, the effect of medium dose group was obvious. Although there was a trend of down-regulation in the cortical administration group, there was no statistical significance.(4) Changes in Ca2+concentration in the brain. Detection of intracellular Ca2 +concentration in AD mice by OST doses showed that,compared with the sham group, the model group was significantly upregulated in cortical Ca2 +levels.There was no statistical difference in the administration group. Compared with the model group, the concentration of Ca2+in the OST-H group significantly decreased.(5) Effect on levels of Aβ1-42 in hippocampus and serum: model group had significantly higher Aβ1-42 levels in hippocampus than in sham operation group, which was statistically significant(P<0.05). Aβ1-42 in serum was also significantly upregulated compared to the sham group, which was statistically significant(P<0.05). Compared with the model group, the levels of Aβ1-42 in the OST administration group were significantly down-regulated,with the lower and middle doses in the hippocampus being more significant, while the serum was more pronounced at lower doses.(6) Silver staining to detect the tangles of hippocampal neurons: Neuron tangles in the hippocampal CA1 region showed a dark brown-yellow granule distribution in the nuclei of the model group(positive expression). Nerve cell body and dendrites, axons are black or black red,background light yellow. Compared with the model group, the administration group has improved significantly. CONCLUSION OST improves spatial learning and memory of dementia model mice injected with Aβ25-35 in both hippocampus. Experimental studies have shown that OST has different degrees of regulation on neuronal apoptosis, Ca2 +/GLU/oxidative stress and other pathways, and it plays a role in improving multiple AD pathological changes and delaying the pathogenesis of neurodegenerative diseases.展开更多
The active components associated with the bio-designer drugs known variously as “Spice” or “K2” have rapidly gained in popularity among recreational users, forcing the United States Drug Enforcement Administration...The active components associated with the bio-designer drugs known variously as “Spice” or “K2” have rapidly gained in popularity among recreational users, forcing the United States Drug Enforcement Administration to classify these compounds as Schedule I drugs in the Spring of 2011. However, although there is some information about many of the synthetic cannabinoids used in Spice products, little is known about the consequences of the main constituent, (1-pentyl-3-(1-naphthoyl)indole;JWH-018), on neuropsychological development or behavior. In the present experiment, adolescent rats were given repeated injections of either saline or 100 μg/kg of JWH-018. Once the animals were 75 days of age, they were trained using tasks with spatial components of various levels of difficulty and a spatial learning set task. On early trials with water maze tasks of varying difficulty, the JWH-018 treated rats were impaired relative to controls. However, by the end of each phase of testing, drug and control animals were comparable, although on probe trials the drug-treated animals spent significantly less time in the target quadrant. In addition, the performance of the drug-treated rats was inferior to that of the control animals on a learning set task, suggesting some difficulty in adapting their responses to changing task demands. The results suggest that chronic exposure to this potent cannabinoid CB1 receptor agonist during adolescence is capable of producing a variety of subtle changes affecting spatial learning and memory performance in adulthood, well after the drug exposure period.展开更多
Objective:We aimed to investigate the effects of osthole on learning and memory impairment of AD mice induced by injection of Aβ25-35 and the content of Ca2+、GLU、Ab1-42 in the brain tissue and peripheral blood.Meth...Objective:We aimed to investigate the effects of osthole on learning and memory impairment of AD mice induced by injection of Aβ25-35 and the content of Ca2+、GLU、Ab1-42 in the brain tissue and peripheral blood.Methods:Mice were randomly assigned to sham operation,Aβ25-35,Aβ25-35+Ost-L,Aβ25-35+Ost-M,and Aβ25-35+Ost-H group.Water maze test was performed to assessing spatial learning ability of mice.It is determined that the MDA level and the activity of SOD in the brain tissue of mice in each group by colorimetry.The GLU kit and Ca2+kit were used to detect the GLU,Ca2+in tissue and serum.Elisa was used to detect the expression of Aβ1-42 in the hippocampus and serum of mice.HE staining and silver staining were used to detect neuron apoptosis and pathological changes in brain slices.Results:①Effects of osthole on learning and memory:With the increase of training day,the escape latencies continuously reduced in each experimental group,the escape latencies of the model group was longer on the 1st,2nd,3rd,and 5th days than the normal group,the difference was statistically significant(day 3,4:P<0.05,day 5:P<0.01);compared with the model group,the escaping latency on the fifth day of the OST low-medium high-dose group was significantly shortened,which was statistically significant(P<0.05).②Effects on oxidative stresspathway:the SOD activity of AD mice in the hippocampus model group was lower than that in the normal group,which was statistically significant(P<0.05);The SOD activity in the OST group was higher than that in the model group,which was statistically significant(P<0.05).The MDA content in the model group was significantly higher than that in the normal group(P<0.05).The MDA content in the OST high-dose group was lower than that in the model group,which was statistically significant(P<0.05).③Effects of GLU levels on neurotransmitters:the results of the detection of GLU in cortical area and GLU in serum of AD mice in OST dose groups showed that serum GLU levels in the model group were significantly lower than those in the sham group,which was statistically significant(P<0.05).GLU levels in the cortical area were also significantly higher than those in the sham group,which was statistically significant(P<0.05).Compared with the model group,GLU levels in the OST administration group were significantly downregulated.Among the serum,the effect of medium dose group was obvious.Although there was a trend of down-regulation in the cortical administration group,there was no statistical significance.④Changes in Ca2+concentration in the brain;Detection of intracellular Ca ion concentration in AD mice by OST doses showed that,compared with the sham group,the model group was significantly upregulated in cortical Ca2+levels.There was no statistical difference in the administration group.Compared with the model group,the concentration of Ca2+in the OST-H group significantly decreased.⑤Effect on levels of Ab1-42 in hippocampus and serum:model group had significantly higher Ab1-42 levels in hippocampus than in sham operation group,which was statistically significant(P<0.05).Ab1-42 in serum was also significantly upregulated compared to the sham group,which was statistically significant(P<0.05).Compared with the model group,the levels of Aβ1-42 in the OST administration group were significantly down-regulated,with the lower and middle doses in the hippocampus being more significant,while the serum was more pronounced at lower doses.⑥Silver staining to detect the tangles of hippocampal neurons:Neuron tangles in the hippocampal CA1 region showed a dark brown-yellow granule distribution in the nuclei of the model group(positive expression).Nerve cell body and dendrites,axons are black or black red,background light yellow.Compared with the model group,the administration group has improved significantly.Conclusion:OST improves spatial learning and memory of dementia model mice injected with Ab25-35 in both hippocampus.Experimental studies have shown that OST has different degrees of regulation on neuronal apoptosis,Ca2+/GLU/oxidative stress and other pathways,and it plays a role in improving multiple AD pathological changes and delaying the pathogenesis of neurodegenerative diseases.展开更多
The resulting slag particles from solid rocket motor( SRM) firings are an important component of space debris environment. Slag sizes as large as 1 cm have been witnessed in ground tests,and comparable sizes have been...The resulting slag particles from solid rocket motor( SRM) firings are an important component of space debris environment. Slag sizes as large as 1 cm have been witnessed in ground tests,and comparable sizes have been also estimated via observations of sub-orbital tail-off events. We achieve slag initial data based on MASTER slag model and SRM historical launch data,and propagate slag long-term orbital evolution taking into account the zonal harmonics J2,atmospheric drag,solar radiation pressure and luni-solar attraction to discuss the slag size distribution and orbital characteristics. Finally,future slag debris environment is evaluated based on two different launch rate assumptions. The result shows that current launch frequency will make the slag population sustain growth and the population will not decrease at once even if there are no more launches in the future.展开更多
Along with windblown dust, large quantities of pollutants are annually brought out of the continental by the westerlies in winter and spring; thereafter they are partly subjected to transport by northeastern monsoon w...Along with windblown dust, large quantities of pollutants are annually brought out of the continental by the westerlies in winter and spring; thereafter they are partly subjected to transport by northeastern monsoon winds to Taiwan. Both PM10 and PM2.5 aerosols collected from northern Taiwan from February 2002 to March 2003 were determined for three heavy metals, namely Pb, Cd and Zn, to characterize the heavy metal compositions between long-range transported and local aerosols and to evaluate their contributions of long-range transport during the northeastern monsoon season. Low Cd/Pb (0.017) and Zn/Pb (1.82) ratios were measured in aerosols during the Asian dust period, in which the sources of ambient aerosols are dominated by long-range transport. By contrast, high Cd/Pb(0.030) and Zn/Pb (3.44) ratios were measured during the summer monsoon season, in which local pollutant emissions dominate the sources of heavy metals. Such characteristic Cd/Pb and Zn/Pb ratios appear to be successfully applied to identify the pollutants originated from the long-range transport or local emissions.展开更多
基金funded by China National Science and Technology Support Program(Grant No.2012BAD21B02)
文摘This study aimed to demonstrate change in spatial correlation between Korean pine (Pinus koraiensis Sieb. et Zucc.) and three rare species, and change in spatial distribution of four species in response to a range of selective cutting intensities. We sampled three plots of mixed Korean pine and broad-leaf forest in Lushuihe Forestry Bureau of Jilin province, China. Plot 1, a control, was unlogged Korean pine broad-leaf forest. In plots 2 and 3, Korean pine was selectively cut at 15 and 30 % intensity, respectively, in the 1970s. Other species were rarely cut. We used point-pattern analysis to research the spatial distributions of four tree species and quantify spatial correlations between Korean pine and the other three species, Amur linden (Tilia amurensis Rupr.), Manchurian ash (Fraxinus mandshurica Rupr.), and Mongolian oak (Quercus mongolica Fisch.) in all three plots. The results of the study show that selective cutting at 15 % intensity did not significantly change either the species spatial patterns or the spatial correlation between Korean pine and broadleaf species. Selective cutting at 30 % intensity slightly affected the growth of Korean pine and valuable species in forest communities, and the effect was considered nondestructive and recoverable.
基金Under the auspices of Natural Science Foundation of China(No.42071342,31870713)Beijing Natural Science Foundation Program(No.8182038)Fundamental Research Funds for the Central Universities(No.2015ZCQ-LX-01,2018ZY06)。
文摘With the continuous development of urbanization in China,the country’s growing population brings great challenges to urban development.By mastering the refined population spatial distribution in administrative units,the quantity and agglomeration of population distribution can be estimated and visualized.It will provide a basis for a more rational urban planning.This paper takes Beijing as the research area and uses a new Luojia1-01 nighttime light image with high resolution,land use type data,Points of Interest(POI)data,and other data to construct the population spatial index system,establishing the index weight based on the principal component analysis.The comprehensive weight value of population distribution in the study area was then used to calculate the street population distribution of Beijing in 2018.Then the population spatial distribution was visualize using GIS technology.After accuracy assessments by comparing the result with the WorldPop data,the accuracy has reached 0.74.The proposed method was validated as a qualified method to generate population spatial maps.By contrast of local areas,Luojia 1-01 data is more suitable for population distribution estimation than the NPP/VIIRS(Net Primary Productivity/Visible infrared Imaging Radiometer)nighttime light data.More geospatial big data and mathematical models can be combined to create more accurate population maps in the future.
文摘For a better understanding of the deposition mechanism of thin films in SiCl4 source gas, we have measured the spatial distributions of SiCln (n=0-2) radicals in SICl4 radio frequency glow discharge plasma utilizing a mass spectrometer equipped with a movable gas sampling apparatus. The experimental results demonstrate that the relative densities of SiCln (n=0-2) radicals have peak values at the position of 10 mm above the powered electrode along the axial direction; the relative densities of the Si and SiCIn (n=1, 2) radicals have peak values at the positions of 27mm and 7 mm away from the axis along the radial direction, respectively. Generally speaking, in the whole SICl4 plasma bulk region, the relative density of Si is one order of magnitude higher than that of SICl, and the relative density of SiCl is several times higher than that of SICl2. This reveals that Si and SiCl may be the primary growth precursors in forming thin films.
文摘The Zagros forests are a treasure of valuable oak forests, but they have been severely degraded from long-term misuse. Geographic information systems (GIS) and multi-criteria decision analysis (MCDA) have been increasingly used to improve the management of vulnerable ecosystems to prevent further degradation and increase the sustainability of land use. This study presents a methodology to assess land suitability using remote sensing (RS) to obtain wall-to-wall data for the calculations, GIS to analyze the data, and MCDA to rank alternative land uses. The criteria and subcriteria affecting the suitability of land for different uses were identified and weighted using an analytic hierarchy process. Variables used as subcriteria were assessed using satellite data and other sources of information such as existing maps and field surveys. Numerical values for the subcriteria were classified, and each class was given a priority rating according to expert judgments. Based on the ratings and weights of the subcriteria, a priority map was created for each land use using the weighted linear combination method. The priority maps for different land uses were overlaid to obtain a preliminary land use map, which often indicated several simultaneous land uses for the same location. The preliminary map was further edited by removing unrealistic, mutually exclusive land-use combinations. The study tested and demonstrated the potential of integrating RS, G1S and MCDA techniques for solving complicated land allocation problems in forested regions using a scientifically sound and practical approach for efficient and sustainable allocation of forestland for different uses.
基金supported by the National Natural Science Foundation of China(10772188)
文摘A novel method based on wavelength-multiplexed line-of-sight absorption and profile fitting for nonuniform flow field measurement is reported. A wavelength scanning combing laser temperature and current modulation WMS scheme is used to implement the wavelength-multi- plexed-profile fitting method. Second harmonic (2f) signal of eight H20 transitions features near 7,170 cm^-1 are measured in one period using a single tunable diode laser. Spatial resolved temperature distribution upon a CH4/air premixed flat flame burner is obtained. The result validates the feasibility of strategy for non-uniform flow field diagnostics by means of WMS-2f TDLAS.
文摘On the basis of the emission data of the industrial sulphur dioxide (SO_2) and observed climate fields over East Asia, the distribution of anthropogenic sulfate aerosol(SO_4~2-) with seasonal variation in the troposphere is simulated and analyzed by a regional sulfur transport model, and the direct radiative effects of SO_4~2- under different weather conditions are also calculated using the discrete ordinate method. The results show that the concentration of SO_4~2- has significant seasonal and spatial variations resulting from the effects of SO_2 emission source and precipitation and wind fields. Both the concentration of SO_2 and its radiative forcing have the largest values in October and the lowest in July. SO_4~2- causes the decrease of the radiation flux absorbed by earth-atmosphere and the cooling of air temperature by scattering more solar radiation back into space. Besides, the radiative and climatic effects of SO_4~2- are related to the types and height and optical thickness, etc., of the clouds.
文摘Dynamic load imposed on the bridge by mov- ing vehicle depends on several bridge-vehicle parameters with various uncertainties. In the present paper, particle filter technique based on conditional probability has been used to identify vehicle mass, suspension stiffness, and damping including tyre parameters from simulated bridge accelerations at different locations. A closed-form expres- sion is derived to generate independent response samples for the idealized bridge-vehicle coupled system consider- ing spatially non-homogeneous pavement unevenness. Thereafter, it is interfaced with the iterative process of particle filtering algorithm. The generated response sam- ples are contaminated by adding artificial noise in order to reflect field condition. The mean acceleration time history is utilized in particle filtering technique. The vehicle- imposed dynamic load is reconstructed with the identified parameters and compared with the simulated results. The present identification technique is examined in the presence of different levels of artificial noise with bridge response simulated at different locations. The effect of vehicle velocity, bridge surface roughness, and choice of prior probability density parameters on the efficiency of the method is discussed.
基金National Natural Science Foundation of China(81703901)Shandong Province Natural Science Foundation of China(ZR2016HB56)
文摘OBJECTIVE To investigate the effects of osthole on learning and memory impairment of AD mice induced by injection of Aβ25-35 and the content of Ca2+, GLU and Aβ1-42 in the brain tissue and peripheral blood. METHODS Mice were randomly assigned to sham operation, Aβ25-35, Aβ25-35+Ost-L,Aβ25-35+Ost-M, and Aβ25-35+Ost-H group. Water maze test was performed to assessing spatial learning ability of mice. It is determined that the MDA level and the activity of SOD in the brain tissue of mice in each group by colorimetry. The GLU kit and Ca2 +kit were used to detect the GLU, Ca2 +in tissue and serum. ELISA was used to detect the expression of Aβ1-42 in the hippocampus and serum of mice. HE staining and silver staining were used to detect neuron apoptosis and pathological changes in brain slices and so on. RESULTS(1) Effects of osthole on learning and memory: With the increase of training day,the escape latencies continuously reduced in each experimental group, the escape latencies of the model group was longer on the 1 st, 2 nd, 3 rd, and 5 thdays than the normal group, the difference was statistically significant(day 3 and 4: P<0.05, day 5: P<0.01);compared with the model group, the escaping latency on the 5 thday of the OST low-medium high-dose group was significantly shortened, which was statistically significant(P<0.05).(2) Effects on oxidative stresspathway: the SOD activity of AD mice in the hippocampus model group was lower than that in the normal group, which was statistically significant(P<0.05);The SOD activity in the OST group was higher than that in the model group, which was statistically significant(P<0.05). The MDA content in the model group was significantly higher than that in the normal group(P<0.05). The MDA content in the OST high-dose group was lower than that in the model group, which was statistically significant(P<0.05).(3) Effects of GLU levels on neurotransmitters:the results of the detection of GLU in cortical area and GLU in serum of AD mice in OST dose groups showed that serum GLU levels in the model group were significantly lower than those in the sham group, which was statistically significant(P<0.05). GLU levels in the cortical area were also significantly higher than those in the sham group, which was statistically significant(P<0.05). Compared with the model group, GLU levels in the OST administration group were significantly down-regulated. Among the serum, the effect of medium dose group was obvious. Although there was a trend of down-regulation in the cortical administration group, there was no statistical significance.(4) Changes in Ca2+concentration in the brain. Detection of intracellular Ca2 +concentration in AD mice by OST doses showed that,compared with the sham group, the model group was significantly upregulated in cortical Ca2 +levels.There was no statistical difference in the administration group. Compared with the model group, the concentration of Ca2+in the OST-H group significantly decreased.(5) Effect on levels of Aβ1-42 in hippocampus and serum: model group had significantly higher Aβ1-42 levels in hippocampus than in sham operation group, which was statistically significant(P<0.05). Aβ1-42 in serum was also significantly upregulated compared to the sham group, which was statistically significant(P<0.05). Compared with the model group, the levels of Aβ1-42 in the OST administration group were significantly down-regulated,with the lower and middle doses in the hippocampus being more significant, while the serum was more pronounced at lower doses.(6) Silver staining to detect the tangles of hippocampal neurons: Neuron tangles in the hippocampal CA1 region showed a dark brown-yellow granule distribution in the nuclei of the model group(positive expression). Nerve cell body and dendrites, axons are black or black red,background light yellow. Compared with the model group, the administration group has improved significantly. CONCLUSION OST improves spatial learning and memory of dementia model mice injected with Aβ25-35 in both hippocampus. Experimental studies have shown that OST has different degrees of regulation on neuronal apoptosis, Ca2 +/GLU/oxidative stress and other pathways, and it plays a role in improving multiple AD pathological changes and delaying the pathogenesis of neurodegenerative diseases.
文摘The active components associated with the bio-designer drugs known variously as “Spice” or “K2” have rapidly gained in popularity among recreational users, forcing the United States Drug Enforcement Administration to classify these compounds as Schedule I drugs in the Spring of 2011. However, although there is some information about many of the synthetic cannabinoids used in Spice products, little is known about the consequences of the main constituent, (1-pentyl-3-(1-naphthoyl)indole;JWH-018), on neuropsychological development or behavior. In the present experiment, adolescent rats were given repeated injections of either saline or 100 μg/kg of JWH-018. Once the animals were 75 days of age, they were trained using tasks with spatial components of various levels of difficulty and a spatial learning set task. On early trials with water maze tasks of varying difficulty, the JWH-018 treated rats were impaired relative to controls. However, by the end of each phase of testing, drug and control animals were comparable, although on probe trials the drug-treated animals spent significantly less time in the target quadrant. In addition, the performance of the drug-treated rats was inferior to that of the control animals on a learning set task, suggesting some difficulty in adapting their responses to changing task demands. The results suggest that chronic exposure to this potent cannabinoid CB1 receptor agonist during adolescence is capable of producing a variety of subtle changes affecting spatial learning and memory performance in adulthood, well after the drug exposure period.
文摘Objective:We aimed to investigate the effects of osthole on learning and memory impairment of AD mice induced by injection of Aβ25-35 and the content of Ca2+、GLU、Ab1-42 in the brain tissue and peripheral blood.Methods:Mice were randomly assigned to sham operation,Aβ25-35,Aβ25-35+Ost-L,Aβ25-35+Ost-M,and Aβ25-35+Ost-H group.Water maze test was performed to assessing spatial learning ability of mice.It is determined that the MDA level and the activity of SOD in the brain tissue of mice in each group by colorimetry.The GLU kit and Ca2+kit were used to detect the GLU,Ca2+in tissue and serum.Elisa was used to detect the expression of Aβ1-42 in the hippocampus and serum of mice.HE staining and silver staining were used to detect neuron apoptosis and pathological changes in brain slices.Results:①Effects of osthole on learning and memory:With the increase of training day,the escape latencies continuously reduced in each experimental group,the escape latencies of the model group was longer on the 1st,2nd,3rd,and 5th days than the normal group,the difference was statistically significant(day 3,4:P<0.05,day 5:P<0.01);compared with the model group,the escaping latency on the fifth day of the OST low-medium high-dose group was significantly shortened,which was statistically significant(P<0.05).②Effects on oxidative stresspathway:the SOD activity of AD mice in the hippocampus model group was lower than that in the normal group,which was statistically significant(P<0.05);The SOD activity in the OST group was higher than that in the model group,which was statistically significant(P<0.05).The MDA content in the model group was significantly higher than that in the normal group(P<0.05).The MDA content in the OST high-dose group was lower than that in the model group,which was statistically significant(P<0.05).③Effects of GLU levels on neurotransmitters:the results of the detection of GLU in cortical area and GLU in serum of AD mice in OST dose groups showed that serum GLU levels in the model group were significantly lower than those in the sham group,which was statistically significant(P<0.05).GLU levels in the cortical area were also significantly higher than those in the sham group,which was statistically significant(P<0.05).Compared with the model group,GLU levels in the OST administration group were significantly downregulated.Among the serum,the effect of medium dose group was obvious.Although there was a trend of down-regulation in the cortical administration group,there was no statistical significance.④Changes in Ca2+concentration in the brain;Detection of intracellular Ca ion concentration in AD mice by OST doses showed that,compared with the sham group,the model group was significantly upregulated in cortical Ca2+levels.There was no statistical difference in the administration group.Compared with the model group,the concentration of Ca2+in the OST-H group significantly decreased.⑤Effect on levels of Ab1-42 in hippocampus and serum:model group had significantly higher Ab1-42 levels in hippocampus than in sham operation group,which was statistically significant(P<0.05).Ab1-42 in serum was also significantly upregulated compared to the sham group,which was statistically significant(P<0.05).Compared with the model group,the levels of Aβ1-42 in the OST administration group were significantly down-regulated,with the lower and middle doses in the hippocampus being more significant,while the serum was more pronounced at lower doses.⑥Silver staining to detect the tangles of hippocampal neurons:Neuron tangles in the hippocampal CA1 region showed a dark brown-yellow granule distribution in the nuclei of the model group(positive expression).Nerve cell body and dendrites,axons are black or black red,background light yellow.Compared with the model group,the administration group has improved significantly.Conclusion:OST improves spatial learning and memory of dementia model mice injected with Ab25-35 in both hippocampus.Experimental studies have shown that OST has different degrees of regulation on neuronal apoptosis,Ca2+/GLU/oxidative stress and other pathways,and it plays a role in improving multiple AD pathological changes and delaying the pathogenesis of neurodegenerative diseases.
基金Sponsored by the Space Debris Special Projects of State Administration of Science Technology and Industry for National Defense(Grant No.K020410-1/2)
文摘The resulting slag particles from solid rocket motor( SRM) firings are an important component of space debris environment. Slag sizes as large as 1 cm have been witnessed in ground tests,and comparable sizes have been also estimated via observations of sub-orbital tail-off events. We achieve slag initial data based on MASTER slag model and SRM historical launch data,and propagate slag long-term orbital evolution taking into account the zonal harmonics J2,atmospheric drag,solar radiation pressure and luni-solar attraction to discuss the slag size distribution and orbital characteristics. Finally,future slag debris environment is evaluated based on two different launch rate assumptions. The result shows that current launch frequency will make the slag population sustain growth and the population will not decrease at once even if there are no more launches in the future.
文摘Along with windblown dust, large quantities of pollutants are annually brought out of the continental by the westerlies in winter and spring; thereafter they are partly subjected to transport by northeastern monsoon winds to Taiwan. Both PM10 and PM2.5 aerosols collected from northern Taiwan from February 2002 to March 2003 were determined for three heavy metals, namely Pb, Cd and Zn, to characterize the heavy metal compositions between long-range transported and local aerosols and to evaluate their contributions of long-range transport during the northeastern monsoon season. Low Cd/Pb (0.017) and Zn/Pb (1.82) ratios were measured in aerosols during the Asian dust period, in which the sources of ambient aerosols are dominated by long-range transport. By contrast, high Cd/Pb(0.030) and Zn/Pb (3.44) ratios were measured during the summer monsoon season, in which local pollutant emissions dominate the sources of heavy metals. Such characteristic Cd/Pb and Zn/Pb ratios appear to be successfully applied to identify the pollutants originated from the long-range transport or local emissions.