An assessment index model was established to evaulate the benefit of the Three-Gorges Reservoir migration through the analytical hierarchy process. Totally 43 indicators were selected to assess the impact of migration...An assessment index model was established to evaulate the benefit of the Three-Gorges Reservoir migration through the analytical hierarchy process. Totally 43 indicators were selected to assess the impact of migration on the economic, social and ecological environmental aspects of the migration communities, with the data of the indicators of the years 1992, 1998, 2002 which represented the period of premigration, the end of the first phase migration and the end of the second phase migration, respectively. The evaluation matrix is sufficiently consistent, with a consistency ratio CR equal to 0.086 3. The assessment turned out a benefit value for the economic subsystem in the year 2004 larger than triple the value in the year 1992, indicating a remarkable economic growth in the Reservoir area. The constantly increasing value for the social subsystem reflects the stable social situations. There is a slight decline in the assessment outcome of the ecological subsystem for the year 1998, which implies enviromental conservation was given insufficient importance during that period. On the whole, the implementation of the migration project is favorable to the Reservoir region, as confirmed by the stably increasing overall evaluation value from 42.22% in 1992 to 68.81% in 2002. However, there is still much room to improve from the status quo to the target criteria.展开更多
The Latin American Migration Project-Colombia is used to study the Body Mass Index (BMI) of Colombian migrants to determine whether their BMI score increased the longer they were abroad. The study contributes to the l...The Latin American Migration Project-Colombia is used to study the Body Mass Index (BMI) of Colombian migrants to determine whether their BMI score increased the longer they were abroad. The study contributes to the literature on BMI by studying Colombian migrants, an understudied migrant group. Duration of trip is used as a measure of acculturation. The study also evaluates the claim that trip duration is a measure of acculturation using data specific to migrants, which shows that trip duration is an adequate proxy measure of acculturation. The study includes current migrants, returned migrants and non-migrants. The study accounts for the selectivity of migration by comparing migrants to non-migrants, as some studies highlight the health selectivity of migration. The study uses multinomial regression to test whether the probability of being overweight and/or obese is associated with spending more time abroad. Consistent with studies conducted within the receiving countries, the study finds that increased duration of trip is positively and significantly associated with the probability of being overweight and obese. Furthermore, the study also shows that among return migrants there is a negative relationship between time they had remained in Colombia and probability of being obese. The findings show that migrants put on weight while abroad and lose that weight the longer they remain in Colombia. The findings show that place has an indelible impact on health through migrant’s weight.展开更多
The transcription factor Sox11 plays important roles in retinal neurogenesis during vertebrate eye development.However,its function in retina regeneration remains elusive.Here we report that Sox11 b,a zebrafish Sox11 ...The transcription factor Sox11 plays important roles in retinal neurogenesis during vertebrate eye development.However,its function in retina regeneration remains elusive.Here we report that Sox11 b,a zebrafish Sox11 homolog,regulates the migration and fate determination of Müller glia-derived progenitors(MGPCs)in an adult zebrafish model of mechanical retinal injury.Following a stab injury,the expression of Sox11 b was induced in proliferating MGPCs in the retina.Sox11 b knockdown did not affect MGPC formation at 4 days post-injury,although the nuclear morphology and subsequent radial migration of MGPCs were alte red.At 7 days post-injury,Sox11 b knockdown res ulted in an increased proportion of MGPCs in the inner retina and a decreased propo rtion of MGPCs in the outer nuclear layer,compared with controls.Furthermore,Sox11 b knockdown led to reduced photoreceptor regeneration,while it increased the numbe rs of newborn amacrines and retinal ganglion cells.Finally,quantitative polymerase chain reaction analysis revealed that Sox11 b regulated the expression of Notch signaling components in the retina,and Notch inhibition partially recapitulated the Sox11 b knockdown phenotype,indicating that Notch signaling functions downstream of Sox11 b.Our findings imply that Sox11 b plays key roles in MGPC migration and fate determination during retina regeneration in zebrafish,which may have critical im plications for future explorations of retinal repair in mammals.展开更多
The ecological environment of the Yellow River Basin has become more fragile under the combined action of natural and manmade activities.However,the change mechanisms of ecological vulnerability in different sub-regio...The ecological environment of the Yellow River Basin has become more fragile under the combined action of natural and manmade activities.However,the change mechanisms of ecological vulnerability in different sub-regions and periods vary,and the reasons for this variability are yet to be explained.Thus,in this study,we proposed a new remote sensing ecological vulnerability index by considering moisture,heat,greenness,dryness,land degradation,and social economy indicators and then analyzed and disclosed the spatial and temporal change patterns of ecological vulnerability of the Yellow River Basin,China from 2000 to 2022 and its driving mechanisms.The results showed that the newly proposed remote sensing ecological vulnerability index had a high accuracy,at 86.36%,which indicated a higher applicability in the Yellow River Basin.From 2000 to 2022,the average remote sensing ecological vulnerability index of the Yellow River Basin was 1.03,denoting moderate vulnerability level.The intensive vulnerability area was the most widely distributed,which was mostly located in the northern part of Shaanxi Province and the eastern part of Shanxi Province.From 2000 to 2022,the ecological vulnerability in the Yellow showed an overall stable trend,while that of the central and eastern regions showed an obvious trend of improvement.The gravity center of ecological vulnerability migrated southwest,indicating that the aggravation of ecological vulnerability in the southwestern regions was more severe than in the northeastern regions of the basin.The dominant single factor of changes in ecological vulnerability shifted from normalized difference vegetation index(NDVI)to temperature from 2000 to 2022,and the interaction factors shifted from temperature∩NDVI to temperature∩precipitation,which indicated that the global climate change exerted a more significant impact on regional ecosystems.The above results could provide decision support for the ecological protection and restoration of the Yellow River Basin.展开更多
Dilatancy-controlled gas flow in preferential pathways plays a key role in the safety analysis of radioactive waste repositories.This is particularly the case for bentonite,an often-preferred barrier material.Gas flow...Dilatancy-controlled gas flow in preferential pathways plays a key role in the safety analysis of radioactive waste repositories.This is particularly the case for bentonite,an often-preferred barrier material.Gas flow in preferential pathways is characterized by localization and spontaneous behavior,which is challenging to simulate in numerical models due to strong hydro-mechanical coupling.To analyze a laboratory experiment in the framework of the DECOVALEX-2023 project,this study introduced a new approach of combining continuous modelling methods with spatial material properties derived from material heterogeneities and experimental observations.The proposed model utilized hydro-mechanical spatial distributions,namely Young’s modulus and gas entry pressure,and elastoplasticity combined with a linear swelling model.A conceptual strain-dependent permeability approach simulated dilatancycontrolled gas flow based on hydro-mechanical coupling.To test the effectiveness of the presented approach,a gas injection test in a compacted,saturated bentonite sample was simulated using the opensource code OpenGeoSys 5.8 and compared with experimental observations.The presented methodology is capable of simulating localized gas flow in preferential pathways.The spatial distributions of Young’s modulus and gas entry pressure affect the swelling pressure,relative permeability and,in combination with the strain-dependent permeability model,also the intrinsic permeability.展开更多
Objective To explore the effects and mechanisms of cytoplasmic M-CSF on the proliferation,migration and invasion of HeLa cells.Methods Both pCMV/cyto/myc vector and pCMV/cyto/myc-M-CSF vector was transfected into HeLa...Objective To explore the effects and mechanisms of cytoplasmic M-CSF on the proliferation,migration and invasion of HeLa cells.Methods Both pCMV/cyto/myc vector and pCMV/cyto/myc-M-CSF vector was transfected into HeLa-cell by transfectaimine.After screening by G418,the positive clones were amplified and confirmed by RT-PCR,Western blot and immunocytochemistry.The effect of cytoplasmic M-CSF on the proliferation of HeLa cells were analyzed by cell conuting and antisense oligonucleotides.The migration and invasion of cell was measured by in vitro Transwell assay and Matrigel-coated polycarbonate filters.The expression of cyclinE,cyclinD1/2/3,CDK2/4/6,Rac1,and matrix metalloproteinase 2 and 9(MMP2/9)were assayed by semiquantitative RT-PCR.And expression of both α-tubulin and cdc42 were displayed by immunofluorescence.The activity of MMP2 was detected by gelatin zymography.Results Results A cell line(referred as to HeLa-M cell)that highly expresses cytoplasmic M-CSF was successfully established in the test.Our result indicated that HeLa-M cell had a larger volume,faster growth rate and shorter doubling time than either pCMV/cyto/myc transfected HeLa cells(referred as to HeLa-C cell)or untransfected HeLa cells(referred as to HeLa cell).M-CSF-specific antisense oligonucleoside significantly inhibited HeLa-M cell proliferation and had little effect on either HeLa-C cell or HeLa-C cell growth.Cytoplasmic M-CSF up-regulated both the expression of cyclinE,cyclinD1 and cyclinD3,CDK2,CDK 4 and CDK6,a Rho GTPase ralative protein(Rac1),cdc42 and MMP2,but had little effect on expression of MMP9 and cyclin D2.Furthermore,cytoplasmic M-CSF induced the rearrangement of the α-tubulin in HeLa cells and significantly promoted the migration and invasion of HeLa cells in vitro.Conclusions Cytoplasmic M-CSFs up-regulate the expression of cyclinE,cyclinD1 and cyclinD3,CDK2,CDK 4 and CDK6 and induces the proliferation of HeLa cells.Cytoplasmic M-CSFs up-regulate the expression of Rac1 and cdc42 and cause the rearrangement of the α-tubulin in HeLa cells.Furthermore Cytoplasmic M-CSFs increase both the expression and activity of MMP2 and promote the migration and invasion of HeLa cell in vitro.But cytoplasmic M-CSFs have little effect on expression of cyclin D2 and MMP9.展开更多
ay equation migration of wide-angle reflections in 2-D medium is one kind of Kirchhoff prestack depth migration method. Based on ray theory, this method can be used extensively in 2-D inhomogeneous medium, and shows i...ay equation migration of wide-angle reflections in 2-D medium is one kind of Kirchhoff prestack depth migration method. Based on ray theory, this method can be used extensively in 2-D inhomogeneous medium, and shows its advantage in wide-angle reflection study. After calculating ray fields, we can get the wave fields of sources and receivers by interpolation, and the intensity (or amplitude) AP corresponding to the depth point P at travel-time tP=tSP+tPR can be found in seismograms. Ray equation migration is completed by transforming AP according to the specific relation, migrating it to the depth point, then calculating the ray fields of lots of sources and receivers in the same way and finally stacking the outcomes. Numerical calculation has yielded satisfactory results. Data processing of the Zhuangmu-Yuexi-Huangmei-Zhanggongdu profile passing through the Dabie orogenic zone provides a structural form of M-discontinuity along the profile. The result shows that the high pressure metamorphic rock zone of South Dabie rock mass is related to the uplifting of M-discontinuity here. 'Mountain root' exists under North Dabie rock mass, which conforms with gravity isostasy theory. The Xiaotian-Mozitan fault is a suture zone as a result of the collision of North China plate with Yangtze plate, and extends through M-discontinuity. The abyssal fault near Liu'an is the extended eastern section of the Luonan-Minggang fault, which is also confirmed here.展开更多
From a dataset of macrobenthos obtained from 18 cruises from 2004 to 2013 in the Huanghe（Yellow River）Estuary and its adjacent areas,the composition and characteristics of macrobenthos were analyzed,and the applicab...From a dataset of macrobenthos obtained from 18 cruises from 2004 to 2013 in the Huanghe（Yellow River）Estuary and its adjacent areas,the composition and characteristics of macrobenthos were analyzed,and the applicability of the Shannon-Wiener Index（H′）,AZTI＇s Marine Biotic Index（AMBI） and multivariate AMBI（MAMBI） for assessing benthic habitat quality was compared.The results showed a total of 203 macrobenthos in the study area.The macrobenthos were dominated by polychaetes,followed by mollusks and crustaceans.The macrobenthic ecological groups were dominated by EGI,EGII and EGIII,which respectively accounted for 31.5%,36.0% and 21.2% of the total.There were significant differences between the evaluation results of the three indices.The ecological quality status（EQS） levels given by the AMBI were greater than those given by the H′ and M-AMBI.The AMBI could not reflect the differences between 11 sites but the H′ and M-AMBI could do.Moreover,the three indices responded well to the variations in salinity（S） and dissolved oxygen（DO） in the waters.The H′ and MAMBI also responded sensitively to the differences in physical parameters,such as water depth and sediment texture.The correlation between M-AMBI and environmental pressure gradient data was the strongest.The MAMBI could effectively distinguish degraded conditions from undegraded but the H′ and AMBI could not.Therefore,the M-AMBI reflected benthic habitat health well in the study areas.However,the objectivity of evaluation results of M-AMBI needs further verification by physical,chemical and biological methods.The thresholds also need further discussion.展开更多
Earth is inhomogeneous, which means its elastic characteristics change with depth. The seismic method employs the propagation of waves throughout the earth to locate different structures and stratigraphy. Understandin...Earth is inhomogeneous, which means its elastic characteristics change with depth. The seismic method employs the propagation of waves throughout the earth to locate different structures and stratigraphy. Understanding the wave propagation is an important matter in exploration seismology;therefore modeling of seismic wave is an important tool. To validate the interpreted earth model out of the seismic data, seismic synthetic seismograms should be generated in a process named “seismic forward modeling”. Finite difference method is used as one of the most common numerical modeling techniques. In this paper the accuracy of finite difference method in seismic section modeling is explored on different modeled data set of heterogeneous earth. It is shown that finite difference method completes with migration to reposition the events in their correct location. Two different migration methods are used and various velocities are also tested to determine an appropriate migration velocity. Finally the validly of finite difference modeling is examined using a 2D structural similarity index technique.展开更多
基金Funded by the Natural Science Foundation of China under the Grant No. 10471159.
文摘An assessment index model was established to evaulate the benefit of the Three-Gorges Reservoir migration through the analytical hierarchy process. Totally 43 indicators were selected to assess the impact of migration on the economic, social and ecological environmental aspects of the migration communities, with the data of the indicators of the years 1992, 1998, 2002 which represented the period of premigration, the end of the first phase migration and the end of the second phase migration, respectively. The evaluation matrix is sufficiently consistent, with a consistency ratio CR equal to 0.086 3. The assessment turned out a benefit value for the economic subsystem in the year 2004 larger than triple the value in the year 1992, indicating a remarkable economic growth in the Reservoir area. The constantly increasing value for the social subsystem reflects the stable social situations. There is a slight decline in the assessment outcome of the ecological subsystem for the year 1998, which implies enviromental conservation was given insufficient importance during that period. On the whole, the implementation of the migration project is favorable to the Reservoir region, as confirmed by the stably increasing overall evaluation value from 42.22% in 1992 to 68.81% in 2002. However, there is still much room to improve from the status quo to the target criteria.
文摘The Latin American Migration Project-Colombia is used to study the Body Mass Index (BMI) of Colombian migrants to determine whether their BMI score increased the longer they were abroad. The study contributes to the literature on BMI by studying Colombian migrants, an understudied migrant group. Duration of trip is used as a measure of acculturation. The study also evaluates the claim that trip duration is a measure of acculturation using data specific to migrants, which shows that trip duration is an adequate proxy measure of acculturation. The study includes current migrants, returned migrants and non-migrants. The study accounts for the selectivity of migration by comparing migrants to non-migrants, as some studies highlight the health selectivity of migration. The study uses multinomial regression to test whether the probability of being overweight and/or obese is associated with spending more time abroad. Consistent with studies conducted within the receiving countries, the study finds that increased duration of trip is positively and significantly associated with the probability of being overweight and obese. Furthermore, the study also shows that among return migrants there is a negative relationship between time they had remained in Colombia and probability of being obese. The findings show that migrants put on weight while abroad and lose that weight the longer they remain in Colombia. The findings show that place has an indelible impact on health through migrant’s weight.
基金supported by the National Key Research and Development Project of China,Nos.2017YFA0104100(to JL),2017YFA0701304(to HX)National Natural Science Foundation of China Nos.81970820(to HX),31930068(to JL)。
文摘The transcription factor Sox11 plays important roles in retinal neurogenesis during vertebrate eye development.However,its function in retina regeneration remains elusive.Here we report that Sox11 b,a zebrafish Sox11 homolog,regulates the migration and fate determination of Müller glia-derived progenitors(MGPCs)in an adult zebrafish model of mechanical retinal injury.Following a stab injury,the expression of Sox11 b was induced in proliferating MGPCs in the retina.Sox11 b knockdown did not affect MGPC formation at 4 days post-injury,although the nuclear morphology and subsequent radial migration of MGPCs were alte red.At 7 days post-injury,Sox11 b knockdown res ulted in an increased proportion of MGPCs in the inner retina and a decreased propo rtion of MGPCs in the outer nuclear layer,compared with controls.Furthermore,Sox11 b knockdown led to reduced photoreceptor regeneration,while it increased the numbe rs of newborn amacrines and retinal ganglion cells.Finally,quantitative polymerase chain reaction analysis revealed that Sox11 b regulated the expression of Notch signaling components in the retina,and Notch inhibition partially recapitulated the Sox11 b knockdown phenotype,indicating that Notch signaling functions downstream of Sox11 b.Our findings imply that Sox11 b plays key roles in MGPC migration and fate determination during retina regeneration in zebrafish,which may have critical im plications for future explorations of retinal repair in mammals.
基金funded by the National Natural Science Foundation of China(42471329,42101306,42301102)the Natural Science Foundation of Shandong Province(ZR2021MD047)+1 种基金the Scientific Innovation Project for Young Scientists in Shandong Provincial Universities(2022KJ224)the Gansu Youth Science and Technology Fund Program(24JRRA100).
文摘The ecological environment of the Yellow River Basin has become more fragile under the combined action of natural and manmade activities.However,the change mechanisms of ecological vulnerability in different sub-regions and periods vary,and the reasons for this variability are yet to be explained.Thus,in this study,we proposed a new remote sensing ecological vulnerability index by considering moisture,heat,greenness,dryness,land degradation,and social economy indicators and then analyzed and disclosed the spatial and temporal change patterns of ecological vulnerability of the Yellow River Basin,China from 2000 to 2022 and its driving mechanisms.The results showed that the newly proposed remote sensing ecological vulnerability index had a high accuracy,at 86.36%,which indicated a higher applicability in the Yellow River Basin.From 2000 to 2022,the average remote sensing ecological vulnerability index of the Yellow River Basin was 1.03,denoting moderate vulnerability level.The intensive vulnerability area was the most widely distributed,which was mostly located in the northern part of Shaanxi Province and the eastern part of Shanxi Province.From 2000 to 2022,the ecological vulnerability in the Yellow showed an overall stable trend,while that of the central and eastern regions showed an obvious trend of improvement.The gravity center of ecological vulnerability migrated southwest,indicating that the aggravation of ecological vulnerability in the southwestern regions was more severe than in the northeastern regions of the basin.The dominant single factor of changes in ecological vulnerability shifted from normalized difference vegetation index(NDVI)to temperature from 2000 to 2022,and the interaction factors shifted from temperature∩NDVI to temperature∩precipitation,which indicated that the global climate change exerted a more significant impact on regional ecosystems.The above results could provide decision support for the ecological protection and restoration of the Yellow River Basin.
基金This research was conducted within the DECOVALEX-2023 projectDECOVALEX is an international research project comprising participants from industry,government,and academia,focusing on development of understanding,models and codes in complex coupled problems in sub-surface geological and engineering applications.DECOVALEX-2023 is the current phase of the project.The authors appreciate the DECOVALEX-2023 Funding Organisations Andra,BASE,BGE,BGR,CAS,CNSC,COVRA,US DOE,ENRESA,ENSI,JAEA,KAERI,NWMO,RWM,SÚRAO,SSM and Taipower for their financial and technical support of the work described in this paper.The statements made in the paper are,however,solely those of the authors and do not necessarily reflect those of the Funding Organisations.This work was further supported by the German Federal Ministry for Economic Affairs and Climate Action(BMWK).
文摘Dilatancy-controlled gas flow in preferential pathways plays a key role in the safety analysis of radioactive waste repositories.This is particularly the case for bentonite,an often-preferred barrier material.Gas flow in preferential pathways is characterized by localization and spontaneous behavior,which is challenging to simulate in numerical models due to strong hydro-mechanical coupling.To analyze a laboratory experiment in the framework of the DECOVALEX-2023 project,this study introduced a new approach of combining continuous modelling methods with spatial material properties derived from material heterogeneities and experimental observations.The proposed model utilized hydro-mechanical spatial distributions,namely Young’s modulus and gas entry pressure,and elastoplasticity combined with a linear swelling model.A conceptual strain-dependent permeability approach simulated dilatancycontrolled gas flow based on hydro-mechanical coupling.To test the effectiveness of the presented approach,a gas injection test in a compacted,saturated bentonite sample was simulated using the opensource code OpenGeoSys 5.8 and compared with experimental observations.The presented methodology is capable of simulating localized gas flow in preferential pathways.The spatial distributions of Young’s modulus and gas entry pressure affect the swelling pressure,relative permeability and,in combination with the strain-dependent permeability model,also the intrinsic permeability.
文摘Objective To explore the effects and mechanisms of cytoplasmic M-CSF on the proliferation,migration and invasion of HeLa cells.Methods Both pCMV/cyto/myc vector and pCMV/cyto/myc-M-CSF vector was transfected into HeLa-cell by transfectaimine.After screening by G418,the positive clones were amplified and confirmed by RT-PCR,Western blot and immunocytochemistry.The effect of cytoplasmic M-CSF on the proliferation of HeLa cells were analyzed by cell conuting and antisense oligonucleotides.The migration and invasion of cell was measured by in vitro Transwell assay and Matrigel-coated polycarbonate filters.The expression of cyclinE,cyclinD1/2/3,CDK2/4/6,Rac1,and matrix metalloproteinase 2 and 9(MMP2/9)were assayed by semiquantitative RT-PCR.And expression of both α-tubulin and cdc42 were displayed by immunofluorescence.The activity of MMP2 was detected by gelatin zymography.Results Results A cell line(referred as to HeLa-M cell)that highly expresses cytoplasmic M-CSF was successfully established in the test.Our result indicated that HeLa-M cell had a larger volume,faster growth rate and shorter doubling time than either pCMV/cyto/myc transfected HeLa cells(referred as to HeLa-C cell)or untransfected HeLa cells(referred as to HeLa cell).M-CSF-specific antisense oligonucleoside significantly inhibited HeLa-M cell proliferation and had little effect on either HeLa-C cell or HeLa-C cell growth.Cytoplasmic M-CSF up-regulated both the expression of cyclinE,cyclinD1 and cyclinD3,CDK2,CDK 4 and CDK6,a Rho GTPase ralative protein(Rac1),cdc42 and MMP2,but had little effect on expression of MMP9 and cyclin D2.Furthermore,cytoplasmic M-CSF induced the rearrangement of the α-tubulin in HeLa cells and significantly promoted the migration and invasion of HeLa cells in vitro.Conclusions Cytoplasmic M-CSFs up-regulate the expression of cyclinE,cyclinD1 and cyclinD3,CDK2,CDK 4 and CDK6 and induces the proliferation of HeLa cells.Cytoplasmic M-CSFs up-regulate the expression of Rac1 and cdc42 and cause the rearrangement of the α-tubulin in HeLa cells.Furthermore Cytoplasmic M-CSFs increase both the expression and activity of MMP2 and promote the migration and invasion of HeLa cell in vitro.But cytoplasmic M-CSFs have little effect on expression of cyclin D2 and MMP9.
文摘ay equation migration of wide-angle reflections in 2-D medium is one kind of Kirchhoff prestack depth migration method. Based on ray theory, this method can be used extensively in 2-D inhomogeneous medium, and shows its advantage in wide-angle reflection study. After calculating ray fields, we can get the wave fields of sources and receivers by interpolation, and the intensity (or amplitude) AP corresponding to the depth point P at travel-time tP=tSP+tPR can be found in seismograms. Ray equation migration is completed by transforming AP according to the specific relation, migrating it to the depth point, then calculating the ray fields of lots of sources and receivers in the same way and finally stacking the outcomes. Numerical calculation has yielded satisfactory results. Data processing of the Zhuangmu-Yuexi-Huangmei-Zhanggongdu profile passing through the Dabie orogenic zone provides a structural form of M-discontinuity along the profile. The result shows that the high pressure metamorphic rock zone of South Dabie rock mass is related to the uplifting of M-discontinuity here. 'Mountain root' exists under North Dabie rock mass, which conforms with gravity isostasy theory. The Xiaotian-Mozitan fault is a suture zone as a result of the collision of North China plate with Yangtze plate, and extends through M-discontinuity. The abyssal fault near Liu'an is the extended eastern section of the Luonan-Minggang fault, which is also confirmed here.
基金The National Natural Science Foundation of China-Shandong Joint Fund for Marine Science Research Centers under contract No.U1406403the National Marine Public Welfare Research Project of China under contract No.201405007the Environmental Assessment Projects of State Oceanic Administration People's Republic of China under contract No.DOMEP(MEA)-01-01
文摘From a dataset of macrobenthos obtained from 18 cruises from 2004 to 2013 in the Huanghe（Yellow River）Estuary and its adjacent areas,the composition and characteristics of macrobenthos were analyzed,and the applicability of the Shannon-Wiener Index（H′）,AZTI＇s Marine Biotic Index（AMBI） and multivariate AMBI（MAMBI） for assessing benthic habitat quality was compared.The results showed a total of 203 macrobenthos in the study area.The macrobenthos were dominated by polychaetes,followed by mollusks and crustaceans.The macrobenthic ecological groups were dominated by EGI,EGII and EGIII,which respectively accounted for 31.5%,36.0% and 21.2% of the total.There were significant differences between the evaluation results of the three indices.The ecological quality status（EQS） levels given by the AMBI were greater than those given by the H′ and M-AMBI.The AMBI could not reflect the differences between 11 sites but the H′ and M-AMBI could do.Moreover,the three indices responded well to the variations in salinity（S） and dissolved oxygen（DO） in the waters.The H′ and MAMBI also responded sensitively to the differences in physical parameters,such as water depth and sediment texture.The correlation between M-AMBI and environmental pressure gradient data was the strongest.The MAMBI could effectively distinguish degraded conditions from undegraded but the H′ and AMBI could not.Therefore,the M-AMBI reflected benthic habitat health well in the study areas.However,the objectivity of evaluation results of M-AMBI needs further verification by physical,chemical and biological methods.The thresholds also need further discussion.
文摘Earth is inhomogeneous, which means its elastic characteristics change with depth. The seismic method employs the propagation of waves throughout the earth to locate different structures and stratigraphy. Understanding the wave propagation is an important matter in exploration seismology;therefore modeling of seismic wave is an important tool. To validate the interpreted earth model out of the seismic data, seismic synthetic seismograms should be generated in a process named “seismic forward modeling”. Finite difference method is used as one of the most common numerical modeling techniques. In this paper the accuracy of finite difference method in seismic section modeling is explored on different modeled data set of heterogeneous earth. It is shown that finite difference method completes with migration to reposition the events in their correct location. Two different migration methods are used and various velocities are also tested to determine an appropriate migration velocity. Finally the validly of finite difference modeling is examined using a 2D structural similarity index technique.
