Correct definition and management of sponsor- investigator relationship is of central importance for planing and executing clinical trials. During the last decade, there have been numerous modifications of guidelindes...Correct definition and management of sponsor- investigator relationship is of central importance for planing and executing clinical trials. During the last decade, there have been numerous modifications of guidelindes, international and national legislations and regulations. This implicated various alterations and shifts of essential responsibilities and tasks relating to the investigator, sponsor or sponsor-investigator what raised financial, clinical and ethical issues. First experiences with these new regulations and legislations are discussed together with international differences and their impacts on clinical trials. Regarding non-commercial trials and institutional sponsorship, there are still open organizational and legal questions after national implementation of the Europeam Clinical Trials Directive in 2004, although various approaches have been suggested in recent years in Europe. Current trends and controversies are discussed as well. A literature review was performed summarizing recent experiences with current legislations and risen controversies of these new legislations showing impact on future trends.展开更多
The number of clinical trials conducted in China's Mainland,including investigator‐initiated trials(IITs),has increased rapidly in recent years.However,there are few data on the characteristics of cancer‐related...The number of clinical trials conducted in China's Mainland,including investigator‐initiated trials(IITs),has increased rapidly in recent years.However,there are few data on the characteristics of cancer‐related IITs.We performed a comprehensive analysis of the landscape of cancer‐related IITs in China's Mainland in the past decade.All cancer‐related IITs registered on two clinical trial registries in the United States(www.clinicaltrials.gov,CT.gov)and China's Mainland(www.chictr.org.cn,ChiCTR)from 2010 to 2019 were identified.IITs were reviewed manually to validate classification,subcategorized by cancer type,and stratified by design characteristics to facilitate comparison across cancer types and with other specialties.A total of 8199 cancer‐related IITs were identified.The number of trials registered annually increased over time,especially in the last 5 years.Although interventional studies were predominant,randomized double‐blind studies accounted for only 8%of IITs.In the past decade,the trend for interventional studies conducted with different drugs increased year on year,although the increase in hormonal therapy IITs was not significant.Additionally,cancerrelated IITs were unevenly geographically distributed,with half concentrated in the economically developed cities Shanghai,Beijing,and Guangdong.We also found an increase in registration before participant enrollment(64.9%for trials in conducted in 2015–2019 vs.40.2%in 2010–2014,p<0.001)and data monitoring committee use(44.5%vs.40.0%,p=0.001)and a decrease in randomization(51.5%vs.62.7%,p<0.001)and funding(36.4%vs.56.3%,p<0.001)between these periods.We also observed changes in intervention type(decrease in cytotoxic drug therapy[34.8%vs.48.9%,p<0.001];increase in targeted therapy[17.8%vs.14.2%,p=0.004],immune checkpoint inhibitor therapy[6.6%vs.0.0%,p<0.001],and immune cell therapy[9.6%vs.4.5%,p<0.001]).Details of cancer‐related IITs conducted during the past decade illustrate the merits of oncology research in China's Mainland.Although the increased quantity of IITs is encouraging,limitations remain regarding the quality of clinical trials,regional imbalances,and funding allocation.展开更多
The boundary condition is a crucial factor affecting the permeability variation due to suffusion.An experimental investigation on the permeability of gap-graded soil due to horizontal suffusion considering the boundar...The boundary condition is a crucial factor affecting the permeability variation due to suffusion.An experimental investigation on the permeability of gap-graded soil due to horizontal suffusion considering the boundary effect is conducted,where the hydraulic head difference(DH)varies,and the boundary includes non-loss and soil-loss conditions.Soil samples are filled into seven soil storerooms connected in turn.After evaluation,the variation in content of fine sand(ΔR_(f))and the hydraulic conductivity of soils in each storeroom(C_(i))are analyzed.In the non-loss test,the soil sample filling area is divided into runoff,transited,and accumulated areas according to the negative or positive ΔR_(f) values.ΔR_(f) increases from negative to positive along the seepage path,and Ci decreases from runoff area to transited area and then rebounds in accumulated area.In the soil-loss test,all soil sample filling areas belong to the runoff area,where the gentle-loss,strengthened-loss,and alleviated-loss parts are further divided.ΔR_(f) decreases from the gentle-loss part to the strengthened-loss part and then rebounds in the alleviated-loss part,and C_(i) increases and then decreases along the seepage path.The relationship between ΔR_(f) and Ci is different with the boundary condition.Ci exponentially decreases with ΔR_(f) in the non-loss test and increases with ΔR_(f) generally in the soil-loss test.展开更多
A trigger system is typically employed in active seismic testing to trigger and synchronize multichannel surface wave data acquisition.The effect of the trigger system on the dispersion image of surface waves is empir...A trigger system is typically employed in active seismic testing to trigger and synchronize multichannel surface wave data acquisition.The effect of the trigger system on the dispersion image of surface waves is empirically known to be negligible,however,theoretical explanation regarding the effect of the trigger system is insufficient.This study systematically examines the theory for surface wave dispersion analysis and proves that the effect of the trigger system on a dispersion image is negligible via a solid theoretical explanation.Subsequently,based on the new theoretical explanation,an alternative method that uses only the relative phase difference between sensors to extract dispersion characteristics with better conceptual clarity is proposed.Two active surface wave testing cases are considered to validate the theory and method.The results indicate that(1)an accurate trigger system is not necessary for surface wave data acquisition,and(2)it is unnecessary to assume that the impact point is the generation point of the surface waves for the experimental dispersion analysis.展开更多
A novel three-dimensional-fiber reinforced soft pneumatic actuator(3D-FRSPA)inspired by crab claw and human hand structure that can bend and deform independently in each segment is proposed.It has an omni-directional ...A novel three-dimensional-fiber reinforced soft pneumatic actuator(3D-FRSPA)inspired by crab claw and human hand structure that can bend and deform independently in each segment is proposed.It has an omni-directional bending configuration,and the fibers twined symmetrically on both sides to improve the bending performance of FRSPA.In this paper,the static and kinematic analysis of 3D-FRSPA are carried out in detail.The effects of fiber,pneumatic chamber and segment length,and circular air chamber radius of 3D-FRSPA on the mechanical performance of the actuator are discussed,respectively.The soft mobile robot composed of 3D-FRSPA has the ability to crawl.Finally,the crawling processes of the soft mobile robot on different road conditions are studied,respectively,and the motion mechanism of the mobile actuator is shown.The numerical results show that the soft mobile robots have a good comprehensive performance,which verifies the correctness of the proposedmodel.This work shows that the proposed structures have great potential in complex road conditions,unknown space detection and other operations.展开更多
The auto-parametric resonance of a continuous-beam bridge model subjected to a two-point periodic excitation is experimentally and numerically investigated in this study.An auto-parametric resonance experiment of the ...The auto-parametric resonance of a continuous-beam bridge model subjected to a two-point periodic excitation is experimentally and numerically investigated in this study.An auto-parametric resonance experiment of the test model is conducted to observe and measure the auto-parametric resonance of a continuous beam under a two-point excitation on columns.The parametric vibration equation is established for the test model using the finite-element method.The auto-parametric resonance stability of the structure is analyzed by using Newmark's method and the energy-growth exponent method.The effects of the phase difference of the two-point excitation on the stability boundaries of auto-parametric resonance are studied for the test model.Compared with the experiment,the numerical instability predictions of auto-parametric resonance are consistent with the test phenomena,and the numerical stability boundaries of auto-parametric resonance agree with the experimental ones.For a continuous beam bridge,when the ratio of multipoint excitation frequency(applied to the columns)to natural frequency of the continuous girder is approximately equal to 2,the continuous beam may undergo a strong auto-parametric resonance.Combined with the present experiment and analysis,a hypothesis of Volgograd Bridge's serpentine vibration is discussed.展开更多
Machine learning is currently one of the research hotspots in the field of landslide prediction.To clarify and evaluate the differences in characteristics and prediction effects of different machine learning models,Co...Machine learning is currently one of the research hotspots in the field of landslide prediction.To clarify and evaluate the differences in characteristics and prediction effects of different machine learning models,Conghua District,which is the most prone to landslide disasters in Guangzhou,was selected for landslide susceptibility evaluation.The evaluation factors were selected by using correlation analysis and variance expansion factor method.Applying four machine learning methods namely Logistic Regression(LR),Random Forest(RF),Support Vector Machines(SVM),and Extreme Gradient Boosting(XGB),landslide models were constructed.Comparative analysis and evaluation of the model were conducted through statistical indices and receiver operating characteristic(ROC)curves.The results showed that LR,RF,SVM,and XGB models have good predictive performance for landslide susceptibility,with the area under curve(AUC)values of 0.752,0.965,0.996,and 0.998,respectively.XGB model had the highest predictive ability,followed by RF model,SVM model,and LR model.The frequency ratio(FR)accuracy of LR,RF,SVM,and XGB models was 0.775,0.842,0.759,and 0.822,respectively.RF and XGB models were superior to LR and SVM models,indicating that the integrated algorithm has better predictive ability than a single classification algorithm in regional landslide classification problems.展开更多
To figure out the disease occurrence of landscape plants in the main urban area of Lu'an City,the author investigated the disease occurrence of landscape plants in park green space,residential green space,unit att...To figure out the disease occurrence of landscape plants in the main urban area of Lu'an City,the author investigated the disease occurrence of landscape plants in park green space,residential green space,unit attached green space and main road in the area under administration.The survey results showed that there were 29 species of urban landscape plant diseases,mainly powdery mildew and spot diseases.According to the characteristics of the diseases,the causes and problems of the diseases were analyzed,and the corresponding prevention and control measures were put forward.展开更多
The transition radiation of a charged particle crossing the interface of two media having a monatomic impurity layer is investigated. It is shown that at sliding angles of incidence of a particle on the boundary of th...The transition radiation of a charged particle crossing the interface of two media having a monatomic impurity layer is investigated. It is shown that at sliding angles of incidence of a particle on the boundary of the media, the transition radiation is mainly determined by the properties of the surface layer. The possibility of using transition radiation to study the surface of substances is discussed. In addition, due to the hard radiation present in space, this research may be important for the use of light monoatomic layers as a material for satellite antennas, “solar sails” and cover layers in a future space (interstellar) mission.展开更多
The Investigator 24plex QS Kit(QIAGEN,Hilden,Germany)is a 6-dye fluorescent chemistry short tandem repeat(STR)polymerase chain reaction(PCR)amplification system that simultaneously amplifies 20 of the expanded Combine...The Investigator 24plex QS Kit(QIAGEN,Hilden,Germany)is a 6-dye fluorescent chemistry short tandem repeat(STR)polymerase chain reaction(PCR)amplification system that simultaneously amplifies 20 of the expanded Combined DNA Index System(CODIS)core STR loci,SE33,DYS391,and the standard sex-determining locus,amelogenin,as well as two special internal performance quality sensor controls(QS1 and QS2),which are included in the primer mix to check the PCR performance.This study was designed to be a pilot evaluation of this STR-PCR kit in a Chinese Han population regarding the PCR conditions,sensitivity,precision,accuracy,repeatability,reproducibility,and concordance;tolerance to PCR inhibitors;applicability to real“forensic-type”samples;species specificity;mixture,balance and stutter analyses,and utility in a population investigation.The exhaustive validation studies demonstrated that the Investigator 24plex QS system is accurate,sensitive and robust for STR genotyping.In addition,these genetic markers in the population data in our study indicated that they can also be useful for forensic identification and paternity testing in the Chinese Han population.展开更多
Chinese non-English majors are a large group of English learners.In the process of English pronunciation acquisition,issues such as incomplete phonological knowledge,transfer of mother tongue,and overgeneralization,le...Chinese non-English majors are a large group of English learners.In the process of English pronunciation acquisition,issues such as incomplete phonological knowledge,transfer of mother tongue,and overgeneralization,lead to confusion of phonemes and stress,misunderstanding of syllable structure,and errors of assimilation,drop,and epenthesis.The accuracy of English pronunciation can only be improved by knowing both English and Chinese phonological systems,strengthening the teaching of English phonological knowledge,and adopting various phonological training activities.展开更多
This study constructs a preliminary inventory of landslides triggered by the M_(S) 6.8 Luding earthquake based on field investigation and human-computer interaction visual interpretation on optical satellite images.Th...This study constructs a preliminary inventory of landslides triggered by the M_(S) 6.8 Luding earthquake based on field investigation and human-computer interaction visual interpretation on optical satellite images.The results show that this earthquake triggered at least 5007 landslides,with a total landslide area of 17.36 km^(2),of which the smallest landslide area is 65 m^(2)and the largest landslide area reaches 120747 m^(2),with an average landslide area of about 3500 m^(2).The obtained landslides are concentrated in the IX intensity zone and the northeast side of the seismogenic fault,and the area density and point density of landslides are 13.8%,and 35.73 km^(-2) peaks with 2 km as the search radius.It should be noted that the number of landslides obtained in this paper will be lower than the actual situation because some areas are covered by clouds and there are no available post-earthquake remote sensing images.Based on the available post-earthquake remote sensing images,the number of landslides triggered by this earthquake is roughly estimated to be up to 10000.This study can be used to support further research on the distribution pattern and risk evaluation of the coseismic landslides in the region,and the prevention and control of landslide hazards in the seismic area.展开更多
AIM:To ascertain the pattern of investigations at first contact in uveitic patients and evaluate compliance to treatment.METHODS:An observational study comprised of 201 uveitic patients presenting for the first time t...AIM:To ascertain the pattern of investigations at first contact in uveitic patients and evaluate compliance to treatment.METHODS:An observational study comprised of 201 uveitic patients presenting for the first time to our centre from January 2019 to June 2020.Detailed information regarding systemic investigations undertaken by specialists at the time of first contact and the cost of these investigations were reviewed on the first visit to our centre.Compliance with the treatment was determined and reasons behind non-compliance were evaluated on the first follow-up in patients who had no improvement in clinical signs and symptoms.RESULTS:The mean age of the study group was 35.35±14.1y and gender composition was 59.7%males and 40.3%females.Anterior uveitis was observed in 45.3%of patients,intermediate uveitis in 31.8%of patients,posterior uveitis in 14.9%of patients and panuveitis in 8.0%of patients.Association with a systemic disease was evident in 17.9%of patients.When compared with standard guidelines and uveitis patterns,systemic investigations were identified to be relevant only in 38.3%of patients.Non-compliance to treatment was documented in 22.4%of patients.Common reasons for non-compliance were inadequate counselling by the treating physician about treatment in 26.7%of patients and a busy schedule at work/school in 22.2%of patients.CONCLUSION:Significant number of investigations performed at first contact is found to be contrary to standard guidelines and are not contributory to the care.About a quarter of patients in this study are found to be non-compliant with the treatment.Compliance is more challenging to achieve in school-going children and working adults.The availability of comprehensive,periodically updated,evidence-based guidelines on the role of investigations and the use of trained counsellors may help to channelize proper evaluation and improve compliance to treatment,respectively,in patients with uveitis.展开更多
Global biodiversity loss and mass extinction of species have raised serious global concerns,especially in fragile ecosystems.Karst forest,a well-known fragile ecosystem,is served as a natural laboratory for biogeograp...Global biodiversity loss and mass extinction of species have raised serious global concerns,especially in fragile ecosystems.Karst forest,a well-known fragile ecosystem,is served as a natural laboratory for biogeographical,ecological,evolutionary,and taxonomic research.However,species richness and distribution patterns in karst forests largely remain unclear.Orchidaceae has been regarded as the“flagship”group of plant diversity.In this study,we use Wanfengshan Nature Reserve in southeast Yunnan,China,as a model to determine the conservation status of orchids in the karst forest by conducting systematic field surveys in the past three years from 2019 to 2022.In total,we identified 78 orchid species in 35 genera in Wanfengshan Nature Reserve.The dominant species were Bulbophyllum andersonii,Eria coronaria,Nervilia mackinnonii and Paphiopedilum micranthum.Multiple life forms were also observed,including epiphyte(14.29%),facultative epiphyte(18.18%),lithophyte(23.38%),and terrestrial(44.15%).Orchid species richness showed a bimodal pattern varied with altitude,the higher richness was recorded at 1,500-1,600 and 1,200-1,300 m,while the minimum was below 1,100 m.Each independent hill is rich in orchid species including‘endemic’species.A total of 25(33.8%)orchid species were considered threatened by the Redlist of Chinese Vascular Plants(Qin et al.,2017),including 3 CR species,5 EN species and 17 VU species.We call for more research addressing the mechanisms of ecological adaption,mycorrhizal interactions,and pollination of orchids in karst forests,and effective ways for recovery and conservation of orchids.展开更多
The structural response of a single-layer reticulated dome to external explosions is shaped by many variables,and the associated uncertainties imply non-deterministic results.Existing deterministic methods for predict...The structural response of a single-layer reticulated dome to external explosions is shaped by many variables,and the associated uncertainties imply non-deterministic results.Existing deterministic methods for predicting the consequences of specific explosions do not account for these uncertainties.Therefore,the impact of the uncertainties associated with these input variables on the structures’response needs to be studied and quantified.In this study,a parametric uncertainty analysis was conducted first.Then,local and global sensitivity analyses were carried out to identify the drivers of the structural dynamic response.A probabilistic structural response model was established based on sensitive variables and a reasonable sample size.Furthermore,some deterministic empirical methods for explosion-resistance design,including the plane blast load model of CONWEP,the curved blast load model under the 50%assurance level,and the 20%mass-increased method,were used for evaluating their reliability.The results of the analyses revealed that the structural response of a single-layer reticulated dome to an external blast loading is lognormally distributed.Evidently,the MB0.5 method based on the curved reflector load model yielded results with a relatively stable assurance rate and reliability,but CONWEP did not;thus,the 1.2MB0.5 method can be used for making high-confidence simple predictions.In addition,the results indicated that the structural response is very sensitive to the explosion parameters.Based on these results,it is suggested that for explosion proofing,setting up a defensive barrier is more effective than structural strengthening.展开更多
文摘Correct definition and management of sponsor- investigator relationship is of central importance for planing and executing clinical trials. During the last decade, there have been numerous modifications of guidelindes, international and national legislations and regulations. This implicated various alterations and shifts of essential responsibilities and tasks relating to the investigator, sponsor or sponsor-investigator what raised financial, clinical and ethical issues. First experiences with these new regulations and legislations are discussed together with international differences and their impacts on clinical trials. Regarding non-commercial trials and institutional sponsorship, there are still open organizational and legal questions after national implementation of the Europeam Clinical Trials Directive in 2004, although various approaches have been suggested in recent years in Europe. Current trends and controversies are discussed as well. A literature review was performed summarizing recent experiences with current legislations and risen controversies of these new legislations showing impact on future trends.
文摘The number of clinical trials conducted in China's Mainland,including investigator‐initiated trials(IITs),has increased rapidly in recent years.However,there are few data on the characteristics of cancer‐related IITs.We performed a comprehensive analysis of the landscape of cancer‐related IITs in China's Mainland in the past decade.All cancer‐related IITs registered on two clinical trial registries in the United States(www.clinicaltrials.gov,CT.gov)and China's Mainland(www.chictr.org.cn,ChiCTR)from 2010 to 2019 were identified.IITs were reviewed manually to validate classification,subcategorized by cancer type,and stratified by design characteristics to facilitate comparison across cancer types and with other specialties.A total of 8199 cancer‐related IITs were identified.The number of trials registered annually increased over time,especially in the last 5 years.Although interventional studies were predominant,randomized double‐blind studies accounted for only 8%of IITs.In the past decade,the trend for interventional studies conducted with different drugs increased year on year,although the increase in hormonal therapy IITs was not significant.Additionally,cancerrelated IITs were unevenly geographically distributed,with half concentrated in the economically developed cities Shanghai,Beijing,and Guangdong.We also found an increase in registration before participant enrollment(64.9%for trials in conducted in 2015–2019 vs.40.2%in 2010–2014,p<0.001)and data monitoring committee use(44.5%vs.40.0%,p=0.001)and a decrease in randomization(51.5%vs.62.7%,p<0.001)and funding(36.4%vs.56.3%,p<0.001)between these periods.We also observed changes in intervention type(decrease in cytotoxic drug therapy[34.8%vs.48.9%,p<0.001];increase in targeted therapy[17.8%vs.14.2%,p=0.004],immune checkpoint inhibitor therapy[6.6%vs.0.0%,p<0.001],and immune cell therapy[9.6%vs.4.5%,p<0.001]).Details of cancer‐related IITs conducted during the past decade illustrate the merits of oncology research in China's Mainland.Although the increased quantity of IITs is encouraging,limitations remain regarding the quality of clinical trials,regional imbalances,and funding allocation.
基金The research work described herein was funded by the National Nature Science Foundation of China(Grant No.41877213).This financial support is gratefully acknowledged.
文摘The boundary condition is a crucial factor affecting the permeability variation due to suffusion.An experimental investigation on the permeability of gap-graded soil due to horizontal suffusion considering the boundary effect is conducted,where the hydraulic head difference(DH)varies,and the boundary includes non-loss and soil-loss conditions.Soil samples are filled into seven soil storerooms connected in turn.After evaluation,the variation in content of fine sand(ΔR_(f))and the hydraulic conductivity of soils in each storeroom(C_(i))are analyzed.In the non-loss test,the soil sample filling area is divided into runoff,transited,and accumulated areas according to the negative or positive ΔR_(f) values.ΔR_(f) increases from negative to positive along the seepage path,and Ci decreases from runoff area to transited area and then rebounds in accumulated area.In the soil-loss test,all soil sample filling areas belong to the runoff area,where the gentle-loss,strengthened-loss,and alleviated-loss parts are further divided.ΔR_(f) decreases from the gentle-loss part to the strengthened-loss part and then rebounds in the alleviated-loss part,and C_(i) increases and then decreases along the seepage path.The relationship between ΔR_(f) and Ci is different with the boundary condition.Ci exponentially decreases with ΔR_(f) in the non-loss test and increases with ΔR_(f) generally in the soil-loss test.
基金Natural Science Foundation of Hubei Province of China for Distinguished Young Scholars (2023AFA099)Natural Science Foundation of Hubei Province of China for Key Projects (Innovation Group) (2023AFA030)National Natural Science Foundation of China (52178471)。
文摘A trigger system is typically employed in active seismic testing to trigger and synchronize multichannel surface wave data acquisition.The effect of the trigger system on the dispersion image of surface waves is empirically known to be negligible,however,theoretical explanation regarding the effect of the trigger system is insufficient.This study systematically examines the theory for surface wave dispersion analysis and proves that the effect of the trigger system on a dispersion image is negligible via a solid theoretical explanation.Subsequently,based on the new theoretical explanation,an alternative method that uses only the relative phase difference between sensors to extract dispersion characteristics with better conceptual clarity is proposed.Two active surface wave testing cases are considered to validate the theory and method.The results indicate that(1)an accurate trigger system is not necessary for surface wave data acquisition,and(2)it is unnecessary to assume that the impact point is the generation point of the surface waves for the experimental dispersion analysis.
基金work is supported by the Fundamental Research Funds for the Central Universities(Grant No.B230205021)the Postgraduate Research&Practice Innovation Program of Jiangsu Province,China(GrantNo.KYCX22_0592).The financial supports are gratefully acknowl-edged.
文摘A novel three-dimensional-fiber reinforced soft pneumatic actuator(3D-FRSPA)inspired by crab claw and human hand structure that can bend and deform independently in each segment is proposed.It has an omni-directional bending configuration,and the fibers twined symmetrically on both sides to improve the bending performance of FRSPA.In this paper,the static and kinematic analysis of 3D-FRSPA are carried out in detail.The effects of fiber,pneumatic chamber and segment length,and circular air chamber radius of 3D-FRSPA on the mechanical performance of the actuator are discussed,respectively.The soft mobile robot composed of 3D-FRSPA has the ability to crawl.Finally,the crawling processes of the soft mobile robot on different road conditions are studied,respectively,and the motion mechanism of the mobile actuator is shown.The numerical results show that the soft mobile robots have a good comprehensive performance,which verifies the correctness of the proposedmodel.This work shows that the proposed structures have great potential in complex road conditions,unknown space detection and other operations.
基金National Natural Science Foundation of China under Grant No.51879191。
文摘The auto-parametric resonance of a continuous-beam bridge model subjected to a two-point periodic excitation is experimentally and numerically investigated in this study.An auto-parametric resonance experiment of the test model is conducted to observe and measure the auto-parametric resonance of a continuous beam under a two-point excitation on columns.The parametric vibration equation is established for the test model using the finite-element method.The auto-parametric resonance stability of the structure is analyzed by using Newmark's method and the energy-growth exponent method.The effects of the phase difference of the two-point excitation on the stability boundaries of auto-parametric resonance are studied for the test model.Compared with the experiment,the numerical instability predictions of auto-parametric resonance are consistent with the test phenomena,and the numerical stability boundaries of auto-parametric resonance agree with the experimental ones.For a continuous beam bridge,when the ratio of multipoint excitation frequency(applied to the columns)to natural frequency of the continuous girder is approximately equal to 2,the continuous beam may undergo a strong auto-parametric resonance.Combined with the present experiment and analysis,a hypothesis of Volgograd Bridge's serpentine vibration is discussed.
基金supported by the projects of the China Geological Survey(DD20221729,DD20190291)Zhuhai Urban Geological Survey(including informatization)(MZCD–2201–008).
文摘Machine learning is currently one of the research hotspots in the field of landslide prediction.To clarify and evaluate the differences in characteristics and prediction effects of different machine learning models,Conghua District,which is the most prone to landslide disasters in Guangzhou,was selected for landslide susceptibility evaluation.The evaluation factors were selected by using correlation analysis and variance expansion factor method.Applying four machine learning methods namely Logistic Regression(LR),Random Forest(RF),Support Vector Machines(SVM),and Extreme Gradient Boosting(XGB),landslide models were constructed.Comparative analysis and evaluation of the model were conducted through statistical indices and receiver operating characteristic(ROC)curves.The results showed that LR,RF,SVM,and XGB models have good predictive performance for landslide susceptibility,with the area under curve(AUC)values of 0.752,0.965,0.996,and 0.998,respectively.XGB model had the highest predictive ability,followed by RF model,SVM model,and LR model.The frequency ratio(FR)accuracy of LR,RF,SVM,and XGB models was 0.775,0.842,0.759,and 0.822,respectively.RF and XGB models were superior to LR and SVM models,indicating that the integrated algorithm has better predictive ability than a single classification algorithm in regional landslide classification problems.
基金Supported by Youth Project of Natural Science Foundation of Anhui Province(2008085QC135)Postdoctoral Workstation Project of West Anhui University(WXBSH2020003)+4 种基金Key Program of Natural Science Research Project for Anhui Universities(KJ2021A0954)Forestry Carbon Sequestration Self-funded Science and Technology Project of Anhui Province(LJH[2022]267)Subject of Lu'an Forestry Bureau(0045021093)School-level Quality Engineering Project of West Anhui University(wxxy2021017)Provincial Quality Engineering Project of West Anhui University(2022jyxm1765).
文摘To figure out the disease occurrence of landscape plants in the main urban area of Lu'an City,the author investigated the disease occurrence of landscape plants in park green space,residential green space,unit attached green space and main road in the area under administration.The survey results showed that there were 29 species of urban landscape plant diseases,mainly powdery mildew and spot diseases.According to the characteristics of the diseases,the causes and problems of the diseases were analyzed,and the corresponding prevention and control measures were put forward.
文摘The transition radiation of a charged particle crossing the interface of two media having a monatomic impurity layer is investigated. It is shown that at sliding angles of incidence of a particle on the boundary of the media, the transition radiation is mainly determined by the properties of the surface layer. The possibility of using transition radiation to study the surface of substances is discussed. In addition, due to the hard radiation present in space, this research may be important for the use of light monoatomic layers as a material for satellite antennas, “solar sails” and cover layers in a future space (interstellar) mission.
基金This study was supported by the General Program of National Natural Science Foundation of China[grant number 81625013 and 81772028]the Shanghai Outstanding Academic Leaders Plan[grant number 2017485]the Shanghai Talent Development Funding[grant number 2017115].
文摘The Investigator 24plex QS Kit(QIAGEN,Hilden,Germany)is a 6-dye fluorescent chemistry short tandem repeat(STR)polymerase chain reaction(PCR)amplification system that simultaneously amplifies 20 of the expanded Combined DNA Index System(CODIS)core STR loci,SE33,DYS391,and the standard sex-determining locus,amelogenin,as well as two special internal performance quality sensor controls(QS1 and QS2),which are included in the primer mix to check the PCR performance.This study was designed to be a pilot evaluation of this STR-PCR kit in a Chinese Han population regarding the PCR conditions,sensitivity,precision,accuracy,repeatability,reproducibility,and concordance;tolerance to PCR inhibitors;applicability to real“forensic-type”samples;species specificity;mixture,balance and stutter analyses,and utility in a population investigation.The exhaustive validation studies demonstrated that the Investigator 24plex QS system is accurate,sensitive and robust for STR genotyping.In addition,these genetic markers in the population data in our study indicated that they can also be useful for forensic identification and paternity testing in the Chinese Han population.
文摘Chinese non-English majors are a large group of English learners.In the process of English pronunciation acquisition,issues such as incomplete phonological knowledge,transfer of mother tongue,and overgeneralization,lead to confusion of phonemes and stress,misunderstanding of syllable structure,and errors of assimilation,drop,and epenthesis.The accuracy of English pronunciation can only be improved by knowing both English and Chinese phonological systems,strengthening the teaching of English phonological knowledge,and adopting various phonological training activities.
基金the National Natural Science Foundation of China(42077259).
文摘This study constructs a preliminary inventory of landslides triggered by the M_(S) 6.8 Luding earthquake based on field investigation and human-computer interaction visual interpretation on optical satellite images.The results show that this earthquake triggered at least 5007 landslides,with a total landslide area of 17.36 km^(2),of which the smallest landslide area is 65 m^(2)and the largest landslide area reaches 120747 m^(2),with an average landslide area of about 3500 m^(2).The obtained landslides are concentrated in the IX intensity zone and the northeast side of the seismogenic fault,and the area density and point density of landslides are 13.8%,and 35.73 km^(-2) peaks with 2 km as the search radius.It should be noted that the number of landslides obtained in this paper will be lower than the actual situation because some areas are covered by clouds and there are no available post-earthquake remote sensing images.Based on the available post-earthquake remote sensing images,the number of landslides triggered by this earthquake is roughly estimated to be up to 10000.This study can be used to support further research on the distribution pattern and risk evaluation of the coseismic landslides in the region,and the prevention and control of landslide hazards in the seismic area.
文摘AIM:To ascertain the pattern of investigations at first contact in uveitic patients and evaluate compliance to treatment.METHODS:An observational study comprised of 201 uveitic patients presenting for the first time to our centre from January 2019 to June 2020.Detailed information regarding systemic investigations undertaken by specialists at the time of first contact and the cost of these investigations were reviewed on the first visit to our centre.Compliance with the treatment was determined and reasons behind non-compliance were evaluated on the first follow-up in patients who had no improvement in clinical signs and symptoms.RESULTS:The mean age of the study group was 35.35±14.1y and gender composition was 59.7%males and 40.3%females.Anterior uveitis was observed in 45.3%of patients,intermediate uveitis in 31.8%of patients,posterior uveitis in 14.9%of patients and panuveitis in 8.0%of patients.Association with a systemic disease was evident in 17.9%of patients.When compared with standard guidelines and uveitis patterns,systemic investigations were identified to be relevant only in 38.3%of patients.Non-compliance to treatment was documented in 22.4%of patients.Common reasons for non-compliance were inadequate counselling by the treating physician about treatment in 26.7%of patients and a busy schedule at work/school in 22.2%of patients.CONCLUSION:Significant number of investigations performed at first contact is found to be contrary to standard guidelines and are not contributory to the care.About a quarter of patients in this study are found to be non-compliant with the treatment.Compliance is more challenging to achieve in school-going children and working adults.The availability of comprehensive,periodically updated,evidence-based guidelines on the role of investigations and the use of trained counsellors may help to channelize proper evaluation and improve compliance to treatment,respectively,in patients with uveitis.
基金supported by Doctoral Program of Yunnan Forestry Technological College(KY(ZD)201905)the Candidates of the Young and Middle Aged Academic Leaders of Yunnan Province[202305AC160024]Shenzhen Key Laboratory for Orchid Conservation and Utilization(OU202201)to Q.Liu.
文摘Global biodiversity loss and mass extinction of species have raised serious global concerns,especially in fragile ecosystems.Karst forest,a well-known fragile ecosystem,is served as a natural laboratory for biogeographical,ecological,evolutionary,and taxonomic research.However,species richness and distribution patterns in karst forests largely remain unclear.Orchidaceae has been regarded as the“flagship”group of plant diversity.In this study,we use Wanfengshan Nature Reserve in southeast Yunnan,China,as a model to determine the conservation status of orchids in the karst forest by conducting systematic field surveys in the past three years from 2019 to 2022.In total,we identified 78 orchid species in 35 genera in Wanfengshan Nature Reserve.The dominant species were Bulbophyllum andersonii,Eria coronaria,Nervilia mackinnonii and Paphiopedilum micranthum.Multiple life forms were also observed,including epiphyte(14.29%),facultative epiphyte(18.18%),lithophyte(23.38%),and terrestrial(44.15%).Orchid species richness showed a bimodal pattern varied with altitude,the higher richness was recorded at 1,500-1,600 and 1,200-1,300 m,while the minimum was below 1,100 m.Each independent hill is rich in orchid species including‘endemic’species.A total of 25(33.8%)orchid species were considered threatened by the Redlist of Chinese Vascular Plants(Qin et al.,2017),including 3 CR species,5 EN species and 17 VU species.We call for more research addressing the mechanisms of ecological adaption,mycorrhizal interactions,and pollination of orchids in karst forests,and effective ways for recovery and conservation of orchids.
基金the financial support from the China Postdoctora Science Foundation (project No. 2021M690406)the financial supports from the National Natural Science Foundation of China (project Nos. 51708521, 51778183)
文摘The structural response of a single-layer reticulated dome to external explosions is shaped by many variables,and the associated uncertainties imply non-deterministic results.Existing deterministic methods for predicting the consequences of specific explosions do not account for these uncertainties.Therefore,the impact of the uncertainties associated with these input variables on the structures’response needs to be studied and quantified.In this study,a parametric uncertainty analysis was conducted first.Then,local and global sensitivity analyses were carried out to identify the drivers of the structural dynamic response.A probabilistic structural response model was established based on sensitive variables and a reasonable sample size.Furthermore,some deterministic empirical methods for explosion-resistance design,including the plane blast load model of CONWEP,the curved blast load model under the 50%assurance level,and the 20%mass-increased method,were used for evaluating their reliability.The results of the analyses revealed that the structural response of a single-layer reticulated dome to an external blast loading is lognormally distributed.Evidently,the MB0.5 method based on the curved reflector load model yielded results with a relatively stable assurance rate and reliability,but CONWEP did not;thus,the 1.2MB0.5 method can be used for making high-confidence simple predictions.In addition,the results indicated that the structural response is very sensitive to the explosion parameters.Based on these results,it is suggested that for explosion proofing,setting up a defensive barrier is more effective than structural strengthening.