Reduced nicotinamide adenine dinucleotide(NADH)plays a crucial role in many biochemical reactions in human metabolism.In this work,a flow-mediated skin fluorescence(FMSF)-postocclusion reactive hyperaemia(PORH)system ...Reduced nicotinamide adenine dinucleotide(NADH)plays a crucial role in many biochemical reactions in human metabolism.In this work,a flow-mediated skin fluorescence(FMSF)-postocclusion reactive hyperaemia(PORH)system was developed for noninvasive and in vivo measurement of NADH fluorescence and its real-time dynamical changes in human skin tissue.The real-time dynamical changes of NADH fluorescence were analyzed with the changes of skin blood flow measured by laser speckle contrast imaging(LSCI)experiments simultaneously with FMSFPORH measurements,which suggests that the dynamical changes of NADH fluorescence would be mainly correlated with the intrinsic changes of NADH level in the skin tissue.In addition,Monte Carlo simulations were applied to understand the impact of optical property changes on the dynamical changes of NADH fluorescence during the PORH process,which further supports that the dynamical changes of NADH fluorescence measured in our system would be intrinsic changes of NADH level in the skin tissue.展开更多
Objective:To analyze the characteristics,dynamic changes,and outcomes of the first imaging manifestations of 3 patients with severe COVID-19 in our hospital.Methods:Computed tomography(CT)findings of 3 patients with s...Objective:To analyze the characteristics,dynamic changes,and outcomes of the first imaging manifestations of 3 patients with severe COVID-19 in our hospital.Methods:Computed tomography(CT)findings of 3 patients with severe COVID-19 who tested positive by the nucleic acid test in our hospital were selected,mainly focusing on the morphology,distribution characteristics,and dynamic changes of the first CT findings.Results:3 patients with severe pneumonia were older,with one aged 80.The first chest CT examination for all 3 patients differed.Imaging showed a leafy distribution of consolidation,primarily affecting the lower lobes of both lungs and extending subpleurally.A grid-like pattern was observed,along with changes in the consolidation and air bronchogram.These changes had slower absorption,especially in patients with underlying diseases.Conclusion:CT manifestations of severe COVID-19 have specific characteristics and the analysis of their characteristics and dynamic changes provide valuable insights for clinical treatment.展开更多
The change of state of one map in the network of nonlocal coupled logistic maps at the transition of coherence is studied. With the increase of coupling strength, the network dynamics transits from the incoherent stat...The change of state of one map in the network of nonlocal coupled logistic maps at the transition of coherence is studied. With the increase of coupling strength, the network dynamics transits from the incoherent state into the coherent state. In the process, the iteration of the map first changes from chaos to period state, then from periodic to chaotic state again. For the periodic doubling bifurcations, similar to an isolated map, the largest Lyapunov exponent tends to zero from a negative value. However, the states of coupled maps exhibit complex behavior rather than converge to a few fixed values. The behavior brings a new chimera state of coupled logistic maps. The bifurcation diagram is identical to the phase order of maps iterations. For the bifurcation between 1-band and multi-band chaos, the symmetry of chaotic bands emerges and the transition of the order of iteration direction occurs.展开更多
The impact of socioeconomic development on land-use and land-cover change(LUCC)in river basins varies spatially and temporally.Exploring the spatiotemporal evolutionary trends and drivers of LUCC under regional dispar...The impact of socioeconomic development on land-use and land-cover change(LUCC)in river basins varies spatially and temporally.Exploring the spatiotemporal evolutionary trends and drivers of LUCC under regional disparities is the basis for the sustainable development and management of basins.In this study,the Weihe River Basin(WRB)in China was selected as a typical basin,and the WRB was divided into the upstream of the Weihe River Basin(UWRB),the midstream of the Weihe River Basin(MWRB),the downstream of the Weihe River Basin(DWRB),the Jinghe River Basin(JRB),and the Luohe River Basin(LRB).Based on land-use data(cultivated land,forestland,grassland,built-up land,bare land,and water body)from 1985 to 2020,we analyzed the spatiotemporal heterogeneity of LUCC in the WRB using a land-use transfer matrix and a dynamic change model.The driving forces of LUCC in the WRB in different periods were detected using the GeoDetector,and the selected influencing factors included meteorological factors(precipitation and temperature),natural factors(elevation,slope,soil,and distance to rivers),social factors(distance to national highway,distance to railway,distance to provincial highway,and distance to expressway),and human activity factors(population density and gross domestic product(GDP)).The results indicated that the types and intensities of LUCC conversions showed considerable disparities across different sub-basins,where complex conversions among cultivated land,forestland,and grassland occurred in the LRB,JRB,and UWRB,with higher dynamic change before 2000.The conversion of other land-use types to built-up land was concentrated in the UWRB,MWRB,and DWRB,with substantial increases after 2000.Additionally,the driving effects of the influencing factors on LUCC in each sub-basin also exhibited distinct diversity,with the LRB and JRB being influenced by the meteorological and social factors,and the UWRB,MWRB,and DWRB being driven by human activity factors.Moreover,the interaction of these influencing factors indicated an enhanced effect on LUCC.This study confirmed the spatiotemporal heterogeneity effects of socioeconomic status on LUCC in the WRB under regional differences,contributing to the sustainable development of the whole basin by managing sub-basins according to local conditions.展开更多
Background:As is widely known,an increasing number of forest areas were managed to preserve and enhance the health of forest ecosystems.However,previous research on forest management has often overlooked the importanc...Background:As is widely known,an increasing number of forest areas were managed to preserve and enhance the health of forest ecosystems.However,previous research on forest management has often overlooked the importance of structure-based.Aims:Our objectives were to define the direction of structure-based forest management.Subsequently,we investigated the relationships between forest structure and the regeneration,growth,and mortality of trees under different thinning treatments.Ultimately,the drivers of forest structural change were explored.Methods:On the basis of 92 sites selected from northeastern China,with different recovery time (from 1 to 15years) and different thinning intensities (0–59.9%) since the last thinning.Principal component analysis (PCA)identified relationships among factors determining forest spatial structure.The structural equation model (SEM)was used to analyze the driving factors behind the changes in forest spatial structure after thinning.Results:Light thinning (0–20%trees removed) promoted forest regeneration,and heavy thinning (over 35% of trees removed) facilitated forest growth.However,only moderate thinning (20%–35%trees removed) created a reasonable spatial structure.While dead trees were clustered,and they were hardly affected by thinning intensity.Additionally,thinning intensity,recovery time,and altitude indirectly improve the spatial structure of the forest by influencing diameter at breast height (DBH) and canopy area.Conclusion:Creating larger DBH and canopy area through thinning will promote the formation of complex forest structures,which cultivates healthy and stable forests.展开更多
The decrease of total cultivated area and the lower per capita available arable land resource are now serious problems in Shandong Province, a major agricultural province in China. These problems will become more seri...The decrease of total cultivated area and the lower per capita available arable land resource are now serious problems in Shandong Province, a major agricultural province in China. These problems will become more serious along with the further development of economy. In this paper, based on the statistical information at provincial and county levels, the changes of arable land in Shandong Province and their driving forces during the last 50 years are analyzed. The general changing trends of arable land and per capita available arable land are reducing, and the trends of decrease will continue when the economy is developing. The result of GIS spatial analysis shows that the change of the arable land use in Shandong Province has a regional difference. Eight variables having influences on cultivated land change are analyzed by principal component analysis. The results show that the dynamic development of economy, pressure of social system and progress of scientific techniques in agriculture are the main causes for cultivated land reduction. The principal factors which can be considered as driving forces for arable land change include per capita net living space, total population and per ha grain yield. By using regressive equation, along with analysis on population growth and economic development, cultivated areas in Shandong Province in 2005 and 2010 are predicted respectively. The predicted cultivated areas in Shandong will be 6435.47 thousand hain 2005 and 6336.23 thousand ha in 2010 respectively.展开更多
AIM: To evaluate the dynamic ocular biometric changes of a modified form-deprivation myopia model in young guinea pigs. METHODS: The animals were randomly assigned to two groups: the monocularly deprived facemask grou...AIM: To evaluate the dynamic ocular biometric changes of a modified form-deprivation myopia model in young guinea pigs. METHODS: The animals were randomly assigned to two groups: the monocularly deprived facemask group (MDF, with all the right eyes covered, n=24) and the normal control group(free of facemask, n=24). Each group was then equally divided into four subgroups which were followed up for 2, 4, 6 and 8 weeks, respectively. Parameters measured from every eye included refraction, corneal curvature, axial length and the dry weight of sclera at the posterior pole. RESULTS: All the facemasks remained in place during the follow-up. The covered eyes developed myopia with the vitreous chamber lengthening and the dry weight of posterior sclera reduced at each time point compared with the contralateral uncovered (P<0.05 at all time points). The changes had a linear correlation with the deprivation time (P<0.05). There were no significant differences in all the parameters between the uncovered eyes of MDF group and the normal control group (P>0.05 at all time points). CONCLUSION: Monocular form deprivation with the facemask is highly effective and non-invasive in inducing axial myopia in guinea pigs. The axial myopia is mainly caused by the increased vitreous chamber length and the weakened posterior sclera rigidity. The form-deprivation eye didn't interfere with the natural development of the contralateral eye.展开更多
Using the theory and method of the ecological footprint, and combining the changes of regional land use, resource environment, population, society and economy, this paper calculated the ecological footprint, ecologica...Using the theory and method of the ecological footprint, and combining the changes of regional land use, resource environment, population, society and economy, this paper calculated the ecological footprint, ecological carrying capacity and ecological surplus/loss in 1986-2002 on the Loess Plateau in northern Shaanxi Province. What is more, this paper has put forward the concept of ecological pressure index, set up ecological pressure index models, and ecological security grading systems, and the prediction models of different ecological footprints, ecological carrying capacity, ecological surplus and ecological safety change, and also has assessed the ecological footprint demands of 10,000 yuan GDE The results of this study are as follows: (1) the ecological carrying capacity in northern Shaanxi shows a decreasing trend, the difference of reducing range is the fastest; (2) the ecological footprint appears an increasing trend; (3) ecological pressure index rose to 0.91 from 0.44 during 1986-2002 on the Loess Plateau of northern Shaanxi with an increase of 47%; and (4) the ecological security in the study area is in a critical state, and the ecological oressure index has been increasing rapidlv.展开更多
According to dimensionless analysis of the coalbed methane (CBM) production data of Fanzhuang block in southern Qinshui basin, the dimensionless gas production rate is calculated to quantitatively divide the CBM wel...According to dimensionless analysis of the coalbed methane (CBM) production data of Fanzhuang block in southern Qinshui basin, the dimensionless gas production rate is calculated to quantitatively divide the CBM well production process into four stages, i.e., drai- nage stage, unstable gas production stage, stable gas pro- duction stage, and gas production decline stage. By the material balance method, the coal reservoir permeability change in different stages is quantitatively characterized. The characteristics and control mechanisms of change in coalbed permeability (CICP) during different production stages are concluded on five aspects, i.e., permeability trend variation, controlling mechanism, system energy, phase state compositions, and production performance. The study reveals that CICP is characterized by first decline, then recovery, and finally by increase and is controlled directly by effective stress and matrix shrinkage effects. Further, the duration and intensity of the matrix shrinkage effect are inherently controlled by adsorption and desorp- tion features.展开更多
Based on the data of the repeated gravity observation network in Chinese mainland since 1998, we analyzed the temporal changes of regional gravity field before the 2008 Yutian Ms7.3 earthquake. The result shows some m...Based on the data of the repeated gravity observation network in Chinese mainland since 1998, we analyzed the temporal changes of regional gravity field before the 2008 Yutian Ms7.3 earthquake. The result shows some mid-to-long term (two to ten years) changes during the earthquake' s preparation. Notable fea- tures are a gravity increase lasting several years and a relatively large-scaled gradient zone of gravity change, the former indicating a continuous energy accumulation and the latter a possible location of seismic rupture. These gravity changes showed a trend of increase-accelerated increase-decelerated increase, similar to that of the Tangshan Ms7.8 earthquake in 1976. The maximum accumulated gravity change related to the earthquake reached 200 × 10 -8 ms -2.展开更多
In the present paper, a comparison of the performance between moving cutting data-rescaled range analysis (MC- R/S) and moving cutting data-rescaled variance analysis (MC-V/S) is made. The results clearly indicate...In the present paper, a comparison of the performance between moving cutting data-rescaled range analysis (MC- R/S) and moving cutting data-rescaled variance analysis (MC-V/S) is made. The results clearly indicate that the operating efficiency of the MC-R/S algorithm is higher than that of the MC-V/S algorithm. In our numerical test, the computer time consumed by MC-V/S is approximately 25 times that by MC-R/S for an identical window size in artificial data. Except for the difference in operating efficiency, there are no significant differences in performance between MC-R/S and MC-V/S for the abrupt dynamic change detection. Mc-R/s and MC-V/S both display some degree of anti-noise ability. However, it is important to consider the influences of strong noise on the detection results of MC-R/S and MC-V/S in practical application展开更多
Our study explored the dynamic changes in andthe relationship between the DNA damage marker8-hydroxy-2'-deoxyguanosine (8-OHdG) and theDNA repair marker 8-hydroxyguanine DNAglycosidase 1 (hOGG1) according to the ...Our study explored the dynamic changes in andthe relationship between the DNA damage marker8-hydroxy-2'-deoxyguanosine (8-OHdG) and theDNA repair marker 8-hydroxyguanine DNAglycosidase 1 (hOGG1) according to the length ofoccupational employment in nickel smeltingworkers. One hundred forty nickel-exposedsmelting workers and 140 age-matched unexposedoffice workers were selected from the Jinchangcohort. The 8-OHdG levels in smelting workers wassignificantly higher than in office workers (Z=-8.688,P〈0.05) and the 8-OHdG levels among nickelsmelting workers in the 10-14 y employment lengthcategory was significantly higher than among allpeers. The hOGG1 levels among smelting workerswere significantly lower than those of non-exposedworkers (Z=-8.948, P〈0.05). There were significantdifferences between employment length andhOGG1 levels, with subjects employed in nickelsmelting for 10-14 y showing the highest levels ofhOGG1. Correlation analysis showed positivecorrelations between 8-OHdG and hOGG1 levels(r=0.413; P〈0.01). DNA damage was increased withemployment length among nickel smelting workersand was related to the inhibition of hOGG1 repaircapacity.展开更多
The three-period (1995, 1998 and 2003) remote sensing images in Jinan City, China are selected. And the information of green land, construction land, woodland and water body is extracted by using the image processing ...The three-period (1995, 1998 and 2003) remote sensing images in Jinan City, China are selected. And the information of green land, construction land, woodland and water body is extracted by using the image processing module of remote-sensing software and computerized interpretation module. Both the change table and transfer matrix table of land use area are analyzed by modeling module of remote-sensing software. Then, the Geo-information Tupu is obtained; and the temporal and spatial variation of land use in Jinan City is monitored and analyzed by Geo-information Tupu and transfer matrix. Result shows that land use structure change of Jinan City in the years 1995-1998 shows a transformation from green land to construction land. Area of green land circulating into construction land reaches 62.27 square kilometers, accounting for 25.84% of the initial green land. In the year 1998, areas of woodland and green land are reduced due to the urban expansion of Jinan City. However, with the enhancement of people's awareness of environmental protection, areas of woodland and green land gradually increase in the year 2003, which are still less than those in the year 1995.展开更多
Dear Editor,Multiple evanescent white dot syndrome (MEWDS) was first described in 1984 as a rare, acute, unilateral,multifocal retinochoroidal disorder, typically affecting young myopic women. Previous studies with ...Dear Editor,Multiple evanescent white dot syndrome (MEWDS) was first described in 1984 as a rare, acute, unilateral,multifocal retinochoroidal disorder, typically affecting young myopic women. Previous studies with fluorescein angiography (FA) and electrophysiology suggested that MEWDS to be a disease in the retinal pigment epithelium (RPE) or outer retina, while recent studies with spectral- domain optical coherence tomography (SD-OCT) suggested it may be an outer retinal disease due to observation of hyperreflective material in outer retina and subtle disruptionsof the ellipsoid zone without RPE disruption.展开更多
The pattern evolution and dynamic mechanism of the dynamic changes of regional gravity fields occurring before and after the Wenchuan Ms8.0 earthquake are analyzed, based on five epochs of 1998 -2007 mobile gravity da...The pattern evolution and dynamic mechanism of the dynamic changes of regional gravity fields occurring before and after the Wenchuan Ms8.0 earthquake are analyzed, based on five epochs of 1998 -2007 mobile gravity data from the middle-south section of the north-south seismic belt, and two epochs of field research data collected after the 2008 Wenchuan earthquake in combination with GPS data, leveling observations, and geotectonic environment data. The regional dynamic gravity changes demonstrate the effects of the eastward flow of solid matter in the Qinghai-Tibetan plateau and the preparation of the 2008 Wenchuan earthquake (2- 10 yr). The two most meaningful gravity indicators of the Wcnchuan earthquake preparation are the positive (increasing) gravity changes occurring over many years in the southwest epicenter and the largescale gradient zone of gravity variation, with the cumulative difference between the two sides of the gradient zone of gravity exceeding 200 μGal. The positive gravity changes may facilitate a constant energy accumulation and the gradient belt may support seismic shear breakage. Overall, the gravity changes associated with the earthquake preparation indicate a pattern of accelerating increase-decelerating increase-earthquake occurrence. The Songpan-Ganzi block generally displays a negative gravity change, providing evidence for a local upwarp- ing of the deep crust-mantle and an interior expansion of the deep crust attributable to high temperatures. The viewpoint is consistent with the dilatant mechanism for earthquake preparation.展开更多
The dynamical processes of a typical linear dune including morphological features, dune ridge swing range and crest height were investigated at different monitoring periods in the hinterland of Tengger Desert. The res...The dynamical processes of a typical linear dune including morphological features, dune ridge swing range and crest height were investigated at different monitoring periods in the hinterland of Tengger Desert. The results indicated that the development of linear dune depends on not only the northwesterly prevailing wind, but also the winds from northeast and southwest. The dune ridge swayed along its fundamental strike and took on an eastward movement gradually. The original dune strike was NW70° on August 3, 1994, and then changed to NE15° on April 21, 2001. The dune crest increased by 1.8 m longitudinally, which manifested strong wind-blown sand activities in this region. Wind erosion frequently occured at the bottom of sand dune, while sand accumulation appeared on its mid-upper section. The mean wind erosion depth was 25 cm on the bottom of linear dune and the height difference of the control points on the dune’s ridge was 1.13 m. Although the linear dune swayed laterally, the horizontal displacement of its ridge moved eastward 5.8 m averagely. The swing range of the dune crest line is very distinct, with a maximum value of 13.2 m. The highest site on the K-profile swayed on both sides of the dune ridge and the heights were 19.88 m at the control point K5, 19.61 m at K6 and 19.05 m at K7, respectively. The results indicated that the lateral swing of the linear dune was distinct under the northwesterly wind and it moved toward east gradually.展开更多
We present a comparison of changes in large and sharp solar wind dynamic pressure, observed by several spacecraft, with fast disturbances in the magnetospheric magnetic field, measured by the geosynchronous satellites...We present a comparison of changes in large and sharp solar wind dynamic pressure, observed by several spacecraft, with fast disturbances in the magnetospheric magnetic field, measured by the geosynchronous satellites. More than 260 changes in solar wind pressure during the period 1996-2003 are selected for this study. Large statistics show that an increase (a decrease) in dynamic pressure always results in an increase (a decrease) in the magnitude of geosynchronous magnetic field. The amplitude of response to the geomagnetic field strongly depends on the location of observer relative to the noon meridian, the value of pressure before disturbance, and the change in amplitude of pressure.展开更多
The quantity and quality changes of cropland in Jilin province are analyzed by combining the statistics from 1949 to 1999 and land-use maps interpreted from TM images in 1986 and in 2000. In general, t...The quantity and quality changes of cropland in Jilin province are analyzed by combining the statistics from 1949 to 1999 and land-use maps interpreted from TM images in 1986 and in 2000. In general, the decreasing trend of the cropland in Jilin province was derived from the statistic data in 1949-1999. While since 1983, the cropland area has increased slightly, because of the conversion from other land-use types to cropland. It is showed that the net increase of cropland was about 43.40×10 4 ha. While the quality change of the cropland can be seen from that mainly caused by the conversion from forestland, grassland to cropland and the change mainly took place in the west, where it is ecologically fragile. According to the spatial distribution model, the centroids' move of the cropland and the grain production are calculated, whose directions are not consistent. The impact of the dynamic change of the cropland on food security is further analyzed.展开更多
Lake change,as a mirror of climate change,has obvious indication and warning effect on climate.By extracting information of all lakes in Tibet Plateau from Landsat of the 1970’s,the 1990’s,around 2000 and 2010 based...Lake change,as a mirror of climate change,has obvious indication and warning effect on climate.By extracting information of all lakes in Tibet Plateau from Landsat of the 1970’s,the 1990’s,around 2000 and 2010 based on RS and GIS,and,in combination with on-the-spot investigations to a few representative lakes,the authors展开更多
In order to practice the concept of‘lucid waters and lush mountains are invaluable assets’and promote the green development of agriculture,it is necessary to improve the efficiency of agricultural energy utilization...In order to practice the concept of‘lucid waters and lush mountains are invaluable assets’and promote the green development of agriculture,it is necessary to improve the efficiency of agricultural energy utilization.Based on the panel data of 28 provinces from 1995 to 2018,this paper calculated China’s agricultural energy input from two categories of direct energy and indirect energy,and used EBM(Epsilon-based Measure)mixed distance function model to measure the energy efficiency of agriculture in China.The nuclear density function and spatial autocorrelation were used to analyze the dynamic evolution of agricultural energy efficiency,and the dynamic panel model was used to analyze the influencing factors of agricultural energy efficiency.The results showed that:①From 1995 to 2018,the total agricultural energy input had increased year by year in China,with an average annual growth rate of 2%.Energy input structure changed from indirect energy-based to direct energy-based.Agricultural energy efficiency showed an evolutionary trend of‘rising-stagnating-rising rapidly’in China.The agricultural energy efficiency was generally low in China,and there was a large space for improvement in agricultural energy efficiency.②From 1995 to 2018,the average annual growth rate of agricultural energy efficiency in the eastern,central and western regions was 2.7%,1.9%and 1.4%respectively.In 2018,the agricultural energy efficiency in the eastern,central and western regions was 0.81,0.71 and 0.59 respectively.The gap between regions was expanding rapidly,and the agricultural energy efficiency in the central and western regions needed to be improved.③From 1995 to 2018,the agricultural energy efficiency of each province was polarized and the absolute gap was widened.There was obvious improvement in agricultural energy efficiency in Guangdong,Shandong,Jiangxi,Jiangsu,Liaoning and Tianjin,while the agricultural energy efficiency of Xinjiang,Guizhou,Zhejiang,Shanghai,and Inner Mongolia deteriorated.④From 1995 to 2018,there was no global spatial correlation of China’s agricultural energy efficiency.However,local‘high-high’concentration gradually appeared in the eastern region since 2010.⑤The first lag of energy efficiency had a significant positive impact on agricultural energy efficiency,and agricultural energy efficiency improvement had a time lag.The level of human capital,per capita net income of farmers and the level of urbanizaton had a significant positive impact on agricultural energy efficiency.The disaster rate,the level of development of secondary and tertiary industries,and the level of opening up had a significant negative impact on agricultural energy efficiency.In the implementation of the strategy of rural revitalization,we should focus on the central and western regions,take the cultivation of professional farmers as the key,focus on improving agricultural production conditions,enhance the level of cooperation between regions,exert the leading role of the secondary and tertiary industries,and enhance the ability of agricultural disaster prevention and mitigation.展开更多
基金supported by the Natural Science Foundation of Hubei Province(Grant No.2020CFB380)the Educational Commission of Hubei Province of China(Grant No.Q20191506).
文摘Reduced nicotinamide adenine dinucleotide(NADH)plays a crucial role in many biochemical reactions in human metabolism.In this work,a flow-mediated skin fluorescence(FMSF)-postocclusion reactive hyperaemia(PORH)system was developed for noninvasive and in vivo measurement of NADH fluorescence and its real-time dynamical changes in human skin tissue.The real-time dynamical changes of NADH fluorescence were analyzed with the changes of skin blood flow measured by laser speckle contrast imaging(LSCI)experiments simultaneously with FMSFPORH measurements,which suggests that the dynamical changes of NADH fluorescence would be mainly correlated with the intrinsic changes of NADH level in the skin tissue.In addition,Monte Carlo simulations were applied to understand the impact of optical property changes on the dynamical changes of NADH fluorescence during the PORH process,which further supports that the dynamical changes of NADH fluorescence measured in our system would be intrinsic changes of NADH level in the skin tissue.
基金Qinghai Provincial Health Commission Medical and Health Science and Technology Project Guiding Topics“Analysis of Dynamic Changes in Chest Imaging of New Coronavirus Pneumonia in Qinghai Province”(2022-wjzdx-63)。
文摘Objective:To analyze the characteristics,dynamic changes,and outcomes of the first imaging manifestations of 3 patients with severe COVID-19 in our hospital.Methods:Computed tomography(CT)findings of 3 patients with severe COVID-19 who tested positive by the nucleic acid test in our hospital were selected,mainly focusing on the morphology,distribution characteristics,and dynamic changes of the first CT findings.Results:3 patients with severe pneumonia were older,with one aged 80.The first chest CT examination for all 3 patients differed.Imaging showed a leafy distribution of consolidation,primarily affecting the lower lobes of both lungs and extending subpleurally.A grid-like pattern was observed,along with changes in the consolidation and air bronchogram.These changes had slower absorption,especially in patients with underlying diseases.Conclusion:CT manifestations of severe COVID-19 have specific characteristics and the analysis of their characteristics and dynamic changes provide valuable insights for clinical treatment.
基金Supported by the National Natural Science Foundation of China under Grant Nos 10875076,11305098 and 11147020the Fundamental Research Funds for the Central Universities under Grant No GK201302008the Interdisciplinary Incubation Project of Shaanxi Normal University under Grant No 5
文摘The change of state of one map in the network of nonlocal coupled logistic maps at the transition of coherence is studied. With the increase of coupling strength, the network dynamics transits from the incoherent state into the coherent state. In the process, the iteration of the map first changes from chaos to period state, then from periodic to chaotic state again. For the periodic doubling bifurcations, similar to an isolated map, the largest Lyapunov exponent tends to zero from a negative value. However, the states of coupled maps exhibit complex behavior rather than converge to a few fixed values. The behavior brings a new chimera state of coupled logistic maps. The bifurcation diagram is identical to the phase order of maps iterations. For the bifurcation between 1-band and multi-band chaos, the symmetry of chaotic bands emerges and the transition of the order of iteration direction occurs.
基金supported by the Natural Science Basic Research Program of Shaanxi Province(2019JLZ-15)the Water Science and Technology Program of Shaanxi Province(2018slkj-4)the Research Fund of the State Key Laboratory of Eco-hydraulics in Northwest Arid Region,Xi'an University of Technology(2019KJCXTD-5)。
文摘The impact of socioeconomic development on land-use and land-cover change(LUCC)in river basins varies spatially and temporally.Exploring the spatiotemporal evolutionary trends and drivers of LUCC under regional disparities is the basis for the sustainable development and management of basins.In this study,the Weihe River Basin(WRB)in China was selected as a typical basin,and the WRB was divided into the upstream of the Weihe River Basin(UWRB),the midstream of the Weihe River Basin(MWRB),the downstream of the Weihe River Basin(DWRB),the Jinghe River Basin(JRB),and the Luohe River Basin(LRB).Based on land-use data(cultivated land,forestland,grassland,built-up land,bare land,and water body)from 1985 to 2020,we analyzed the spatiotemporal heterogeneity of LUCC in the WRB using a land-use transfer matrix and a dynamic change model.The driving forces of LUCC in the WRB in different periods were detected using the GeoDetector,and the selected influencing factors included meteorological factors(precipitation and temperature),natural factors(elevation,slope,soil,and distance to rivers),social factors(distance to national highway,distance to railway,distance to provincial highway,and distance to expressway),and human activity factors(population density and gross domestic product(GDP)).The results indicated that the types and intensities of LUCC conversions showed considerable disparities across different sub-basins,where complex conversions among cultivated land,forestland,and grassland occurred in the LRB,JRB,and UWRB,with higher dynamic change before 2000.The conversion of other land-use types to built-up land was concentrated in the UWRB,MWRB,and DWRB,with substantial increases after 2000.Additionally,the driving effects of the influencing factors on LUCC in each sub-basin also exhibited distinct diversity,with the LRB and JRB being influenced by the meteorological and social factors,and the UWRB,MWRB,and DWRB being driven by human activity factors.Moreover,the interaction of these influencing factors indicated an enhanced effect on LUCC.This study confirmed the spatiotemporal heterogeneity effects of socioeconomic status on LUCC in the WRB under regional differences,contributing to the sustainable development of the whole basin by managing sub-basins according to local conditions.
基金financially supported by the Innovation Foundation for Doctoral Program of Forestry Engineering of Northeast Forestry University,grant number:LYGC202117the China Scholarship Council(CSC),grant number:202306600046+1 种基金the Research and Development Plan of Applied Technology in Heilongjiang Province of China,grant number:GA19C006Research and Demonstration on Functional Improvement Technology of Forest Ecological Security Barrier in Heilongjiang Province,grant number:GA21C030。
文摘Background:As is widely known,an increasing number of forest areas were managed to preserve and enhance the health of forest ecosystems.However,previous research on forest management has often overlooked the importance of structure-based.Aims:Our objectives were to define the direction of structure-based forest management.Subsequently,we investigated the relationships between forest structure and the regeneration,growth,and mortality of trees under different thinning treatments.Ultimately,the drivers of forest structural change were explored.Methods:On the basis of 92 sites selected from northeastern China,with different recovery time (from 1 to 15years) and different thinning intensities (0–59.9%) since the last thinning.Principal component analysis (PCA)identified relationships among factors determining forest spatial structure.The structural equation model (SEM)was used to analyze the driving factors behind the changes in forest spatial structure after thinning.Results:Light thinning (0–20%trees removed) promoted forest regeneration,and heavy thinning (over 35% of trees removed) facilitated forest growth.However,only moderate thinning (20%–35%trees removed) created a reasonable spatial structure.While dead trees were clustered,and they were hardly affected by thinning intensity.Additionally,thinning intensity,recovery time,and altitude indirectly improve the spatial structure of the forest by influencing diameter at breast height (DBH) and canopy area.Conclusion:Creating larger DBH and canopy area through thinning will promote the formation of complex forest structures,which cultivates healthy and stable forests.
基金The National Natural Science Foundation of China, No.49971004
文摘The decrease of total cultivated area and the lower per capita available arable land resource are now serious problems in Shandong Province, a major agricultural province in China. These problems will become more serious along with the further development of economy. In this paper, based on the statistical information at provincial and county levels, the changes of arable land in Shandong Province and their driving forces during the last 50 years are analyzed. The general changing trends of arable land and per capita available arable land are reducing, and the trends of decrease will continue when the economy is developing. The result of GIS spatial analysis shows that the change of the arable land use in Shandong Province has a regional difference. Eight variables having influences on cultivated land change are analyzed by principal component analysis. The results show that the dynamic development of economy, pressure of social system and progress of scientific techniques in agriculture are the main causes for cultivated land reduction. The principal factors which can be considered as driving forces for arable land change include per capita net living space, total population and per ha grain yield. By using regressive equation, along with analysis on population growth and economic development, cultivated areas in Shandong Province in 2005 and 2010 are predicted respectively. The predicted cultivated areas in Shandong will be 6435.47 thousand hain 2005 and 6336.23 thousand ha in 2010 respectively.
文摘AIM: To evaluate the dynamic ocular biometric changes of a modified form-deprivation myopia model in young guinea pigs. METHODS: The animals were randomly assigned to two groups: the monocularly deprived facemask group (MDF, with all the right eyes covered, n=24) and the normal control group(free of facemask, n=24). Each group was then equally divided into four subgroups which were followed up for 2, 4, 6 and 8 weeks, respectively. Parameters measured from every eye included refraction, corneal curvature, axial length and the dry weight of sclera at the posterior pole. RESULTS: All the facemasks remained in place during the follow-up. The covered eyes developed myopia with the vitreous chamber lengthening and the dry weight of posterior sclera reduced at each time point compared with the contralateral uncovered (P<0.05 at all time points). The changes had a linear correlation with the deprivation time (P<0.05). There were no significant differences in all the parameters between the uncovered eyes of MDF group and the normal control group (P>0.05 at all time points). CONCLUSION: Monocular form deprivation with the facemask is highly effective and non-invasive in inducing axial myopia in guinea pigs. The axial myopia is mainly caused by the increased vitreous chamber length and the weakened posterior sclera rigidity. The form-deprivation eye didn't interfere with the natural development of the contralateral eye.
基金National Natural Science Foundation of China, No.40371003 Ministry of Education of China, No.01158 Master Research Project of Shaanxi Normal University
文摘Using the theory and method of the ecological footprint, and combining the changes of regional land use, resource environment, population, society and economy, this paper calculated the ecological footprint, ecological carrying capacity and ecological surplus/loss in 1986-2002 on the Loess Plateau in northern Shaanxi Province. What is more, this paper has put forward the concept of ecological pressure index, set up ecological pressure index models, and ecological security grading systems, and the prediction models of different ecological footprints, ecological carrying capacity, ecological surplus and ecological safety change, and also has assessed the ecological footprint demands of 10,000 yuan GDE The results of this study are as follows: (1) the ecological carrying capacity in northern Shaanxi shows a decreasing trend, the difference of reducing range is the fastest; (2) the ecological footprint appears an increasing trend; (3) ecological pressure index rose to 0.91 from 0.44 during 1986-2002 on the Loess Plateau of northern Shaanxi with an increase of 47%; and (4) the ecological security in the study area is in a critical state, and the ecological oressure index has been increasing rapidlv.
基金financial support from the various funding agencies including the Major State Basic Research Development Program of China (973 Program, 2009CB219604)the National Natural Science Foundation of China (41272175)+1 种基金the Key Project of the National Science & Technology (2011ZX05034-001)the China Scholarship Council
文摘According to dimensionless analysis of the coalbed methane (CBM) production data of Fanzhuang block in southern Qinshui basin, the dimensionless gas production rate is calculated to quantitatively divide the CBM well production process into four stages, i.e., drai- nage stage, unstable gas production stage, stable gas pro- duction stage, and gas production decline stage. By the material balance method, the coal reservoir permeability change in different stages is quantitatively characterized. The characteristics and control mechanisms of change in coalbed permeability (CICP) during different production stages are concluded on five aspects, i.e., permeability trend variation, controlling mechanism, system energy, phase state compositions, and production performance. The study reveals that CICP is characterized by first decline, then recovery, and finally by increase and is controlled directly by effective stress and matrix shrinkage effects. Further, the duration and intensity of the matrix shrinkage effect are inherently controlled by adsorption and desorp- tion features.
基金supported by the National Natural Science Foundation of China(40574012)
文摘Based on the data of the repeated gravity observation network in Chinese mainland since 1998, we analyzed the temporal changes of regional gravity field before the 2008 Yutian Ms7.3 earthquake. The result shows some mid-to-long term (two to ten years) changes during the earthquake' s preparation. Notable fea- tures are a gravity increase lasting several years and a relatively large-scaled gradient zone of gravity change, the former indicating a continuous energy accumulation and the latter a possible location of seismic rupture. These gravity changes showed a trend of increase-accelerated increase-decelerated increase, similar to that of the Tangshan Ms7.8 earthquake in 1976. The maximum accumulated gravity change related to the earthquake reached 200 × 10 -8 ms -2.
基金Project supported by the National Basic Research Program of China(Grant No.2012CB955902)the National Natural Science Foundation of China(Grant Nos.41275074,41475073,and 41175084)
文摘In the present paper, a comparison of the performance between moving cutting data-rescaled range analysis (MC- R/S) and moving cutting data-rescaled variance analysis (MC-V/S) is made. The results clearly indicate that the operating efficiency of the MC-R/S algorithm is higher than that of the MC-V/S algorithm. In our numerical test, the computer time consumed by MC-V/S is approximately 25 times that by MC-R/S for an identical window size in artificial data. Except for the difference in operating efficiency, there are no significant differences in performance between MC-R/S and MC-V/S for the abrupt dynamic change detection. Mc-R/s and MC-V/S both display some degree of anti-noise ability. However, it is important to consider the influences of strong noise on the detection results of MC-R/S and MC-V/S in practical application
基金supported by grants from the National Major Special Project of Cancer Early Detection and Treatment in Jinchang City(No.CZB20120064)the Project of Employees Health Status and Disease Burden Trend Study in Nonferrous Metals Corporation(No.JKB20120013)
文摘Our study explored the dynamic changes in andthe relationship between the DNA damage marker8-hydroxy-2'-deoxyguanosine (8-OHdG) and theDNA repair marker 8-hydroxyguanine DNAglycosidase 1 (hOGG1) according to the length ofoccupational employment in nickel smeltingworkers. One hundred forty nickel-exposedsmelting workers and 140 age-matched unexposedoffice workers were selected from the Jinchangcohort. The 8-OHdG levels in smelting workers wassignificantly higher than in office workers (Z=-8.688,P〈0.05) and the 8-OHdG levels among nickelsmelting workers in the 10-14 y employment lengthcategory was significantly higher than among allpeers. The hOGG1 levels among smelting workerswere significantly lower than those of non-exposedworkers (Z=-8.948, P〈0.05). There were significantdifferences between employment length andhOGG1 levels, with subjects employed in nickelsmelting for 10-14 y showing the highest levels ofhOGG1. Correlation analysis showed positivecorrelations between 8-OHdG and hOGG1 levels(r=0.413; P〈0.01). DNA damage was increased withemployment length among nickel smelting workersand was related to the inhibition of hOGG1 repaircapacity.
基金Supported by the Natural Science Foundation of Shandong Province(Y2007E21)the Key Programs for Science and Technology Development of Shandong Province(2006GG2308005)the Soft Science Project of the Shandong Provincial Department of Science and Technology (200624-14)
文摘The three-period (1995, 1998 and 2003) remote sensing images in Jinan City, China are selected. And the information of green land, construction land, woodland and water body is extracted by using the image processing module of remote-sensing software and computerized interpretation module. Both the change table and transfer matrix table of land use area are analyzed by modeling module of remote-sensing software. Then, the Geo-information Tupu is obtained; and the temporal and spatial variation of land use in Jinan City is monitored and analyzed by Geo-information Tupu and transfer matrix. Result shows that land use structure change of Jinan City in the years 1995-1998 shows a transformation from green land to construction land. Area of green land circulating into construction land reaches 62.27 square kilometers, accounting for 25.84% of the initial green land. In the year 1998, areas of woodland and green land are reduced due to the urban expansion of Jinan City. However, with the enhancement of people's awareness of environmental protection, areas of woodland and green land gradually increase in the year 2003, which are still less than those in the year 1995.
文摘Dear Editor,Multiple evanescent white dot syndrome (MEWDS) was first described in 1984 as a rare, acute, unilateral,multifocal retinochoroidal disorder, typically affecting young myopic women. Previous studies with fluorescein angiography (FA) and electrophysiology suggested that MEWDS to be a disease in the retinal pigment epithelium (RPE) or outer retina, while recent studies with spectral- domain optical coherence tomography (SD-OCT) suggested it may be an outer retinal disease due to observation of hyperreflective material in outer retina and subtle disruptionsof the ellipsoid zone without RPE disruption.
基金financially supported by the National Natural Science Foundation of China (40574012,40374031)Key Project of the National Science & Technology Pillar Program in the Eleventh Five-year Plan(2006BAC01B02-02)Monitoring Project of China Earthquake Administration (201210)
文摘The pattern evolution and dynamic mechanism of the dynamic changes of regional gravity fields occurring before and after the Wenchuan Ms8.0 earthquake are analyzed, based on five epochs of 1998 -2007 mobile gravity data from the middle-south section of the north-south seismic belt, and two epochs of field research data collected after the 2008 Wenchuan earthquake in combination with GPS data, leveling observations, and geotectonic environment data. The regional dynamic gravity changes demonstrate the effects of the eastward flow of solid matter in the Qinghai-Tibetan plateau and the preparation of the 2008 Wenchuan earthquake (2- 10 yr). The two most meaningful gravity indicators of the Wcnchuan earthquake preparation are the positive (increasing) gravity changes occurring over many years in the southwest epicenter and the largescale gradient zone of gravity variation, with the cumulative difference between the two sides of the gradient zone of gravity exceeding 200 μGal. The positive gravity changes may facilitate a constant energy accumulation and the gradient belt may support seismic shear breakage. Overall, the gravity changes associated with the earthquake preparation indicate a pattern of accelerating increase-decelerating increase-earthquake occurrence. The Songpan-Ganzi block generally displays a negative gravity change, providing evidence for a local upwarp- ing of the deep crust-mantle and an interior expansion of the deep crust attributable to high temperatures. The viewpoint is consistent with the dilatant mechanism for earthquake preparation.
基金supported by the National Key Basic Research Development Program of China (2009BAC54B01-1)National Natural Science Foundation of China (41071009 and 40701171)
文摘The dynamical processes of a typical linear dune including morphological features, dune ridge swing range and crest height were investigated at different monitoring periods in the hinterland of Tengger Desert. The results indicated that the development of linear dune depends on not only the northwesterly prevailing wind, but also the winds from northeast and southwest. The dune ridge swayed along its fundamental strike and took on an eastward movement gradually. The original dune strike was NW70° on August 3, 1994, and then changed to NE15° on April 21, 2001. The dune crest increased by 1.8 m longitudinally, which manifested strong wind-blown sand activities in this region. Wind erosion frequently occured at the bottom of sand dune, while sand accumulation appeared on its mid-upper section. The mean wind erosion depth was 25 cm on the bottom of linear dune and the height difference of the control points on the dune’s ridge was 1.13 m. Although the linear dune swayed laterally, the horizontal displacement of its ridge moved eastward 5.8 m averagely. The swing range of the dune crest line is very distinct, with a maximum value of 13.2 m. The highest site on the K-profile swayed on both sides of the dune ridge and the heights were 19.88 m at the control point K5, 19.61 m at K6 and 19.05 m at K7, respectively. The results indicated that the lateral swing of the linear dune was distinct under the northwesterly wind and it moved toward east gradually.
基金Project supported by the Russian Foundation for Basic Researches (Grant Nos 04-02-16152 and 04-02-39004), the International Association for the Promotion of Co-operation with Scientists from the New Independent States of the Former Soviet Union (Grant Nos 03-51-3738 and MK-2267.2004.2) and the National Natural Science Foundation of China (Grand Nos 40325010 and 40574069).
文摘We present a comparison of changes in large and sharp solar wind dynamic pressure, observed by several spacecraft, with fast disturbances in the magnetospheric magnetic field, measured by the geosynchronous satellites. More than 260 changes in solar wind pressure during the period 1996-2003 are selected for this study. Large statistics show that an increase (a decrease) in dynamic pressure always results in an increase (a decrease) in the magnitude of geosynchronous magnetic field. The amplitude of response to the geomagnetic field strongly depends on the location of observer relative to the noon meridian, the value of pressure before disturbance, and the change in amplitude of pressure.
基金Knowledge Innovation Project of CASNo.KZCX1-SW-19
文摘The quantity and quality changes of cropland in Jilin province are analyzed by combining the statistics from 1949 to 1999 and land-use maps interpreted from TM images in 1986 and in 2000. In general, the decreasing trend of the cropland in Jilin province was derived from the statistic data in 1949-1999. While since 1983, the cropland area has increased slightly, because of the conversion from other land-use types to cropland. It is showed that the net increase of cropland was about 43.40×10 4 ha. While the quality change of the cropland can be seen from that mainly caused by the conversion from forestland, grassland to cropland and the change mainly took place in the west, where it is ecologically fragile. According to the spatial distribution model, the centroids' move of the cropland and the grain production are calculated, whose directions are not consistent. The impact of the dynamic change of the cropland on food security is further analyzed.
文摘Lake change,as a mirror of climate change,has obvious indication and warning effect on climate.By extracting information of all lakes in Tibet Plateau from Landsat of the 1970’s,the 1990’s,around 2000 and 2010 based on RS and GIS,and,in combination with on-the-spot investigations to a few representative lakes,the authors
文摘In order to practice the concept of‘lucid waters and lush mountains are invaluable assets’and promote the green development of agriculture,it is necessary to improve the efficiency of agricultural energy utilization.Based on the panel data of 28 provinces from 1995 to 2018,this paper calculated China’s agricultural energy input from two categories of direct energy and indirect energy,and used EBM(Epsilon-based Measure)mixed distance function model to measure the energy efficiency of agriculture in China.The nuclear density function and spatial autocorrelation were used to analyze the dynamic evolution of agricultural energy efficiency,and the dynamic panel model was used to analyze the influencing factors of agricultural energy efficiency.The results showed that:①From 1995 to 2018,the total agricultural energy input had increased year by year in China,with an average annual growth rate of 2%.Energy input structure changed from indirect energy-based to direct energy-based.Agricultural energy efficiency showed an evolutionary trend of‘rising-stagnating-rising rapidly’in China.The agricultural energy efficiency was generally low in China,and there was a large space for improvement in agricultural energy efficiency.②From 1995 to 2018,the average annual growth rate of agricultural energy efficiency in the eastern,central and western regions was 2.7%,1.9%and 1.4%respectively.In 2018,the agricultural energy efficiency in the eastern,central and western regions was 0.81,0.71 and 0.59 respectively.The gap between regions was expanding rapidly,and the agricultural energy efficiency in the central and western regions needed to be improved.③From 1995 to 2018,the agricultural energy efficiency of each province was polarized and the absolute gap was widened.There was obvious improvement in agricultural energy efficiency in Guangdong,Shandong,Jiangxi,Jiangsu,Liaoning and Tianjin,while the agricultural energy efficiency of Xinjiang,Guizhou,Zhejiang,Shanghai,and Inner Mongolia deteriorated.④From 1995 to 2018,there was no global spatial correlation of China’s agricultural energy efficiency.However,local‘high-high’concentration gradually appeared in the eastern region since 2010.⑤The first lag of energy efficiency had a significant positive impact on agricultural energy efficiency,and agricultural energy efficiency improvement had a time lag.The level of human capital,per capita net income of farmers and the level of urbanizaton had a significant positive impact on agricultural energy efficiency.The disaster rate,the level of development of secondary and tertiary industries,and the level of opening up had a significant negative impact on agricultural energy efficiency.In the implementation of the strategy of rural revitalization,we should focus on the central and western regions,take the cultivation of professional farmers as the key,focus on improving agricultural production conditions,enhance the level of cooperation between regions,exert the leading role of the secondary and tertiary industries,and enhance the ability of agricultural disaster prevention and mitigation.